One of the frustrating things about technology is the fact that any computer you buy always seems to be out of date the moment it is delivered. There is always something bigger, better, and faster coming along and, just to rub it in, the new models will probably cost about the same.

But it's wrong to assume that your PC is obsolete just because a newer model has come out. That's just part of the computer industry's fiendish plan to get you to buy a new PC every three years or so.

It's perfectly possible to get the latest technology without starting over and buying a new machine. There are various ways to improve performance and add features that won't cost the earth. So let's see see how you can upgrade your computer from standard to first class.

Looking through Windows
For many people, the first item to consider upgrading will be software. If you've got an old PC running Windows 98 or Me you may well be thinking about upgrading to Windows XP.

It's a tempting idea, as you can get the Windows XP Home Edition upgrade for about £85. It looks a lot nicer than Windows 98 or Me, is more stable and it adds plenty of new features, so it's a quick and easy way of giving an old PC a bit of a facelift.

Even so, our advice here is if it ain't broke, don't fix it. If the software you're currently using does all the things that you want it to do then you really don't need to spend money on expensive upgrades.

Admittedly, Windows XP does offer the user a number of welcome improvements, particularly in simplifying tasks such as networking or setting up internet access.

But if your PC is already set up and working properly, Windows XP won't necessarily make it run any better. In fact, you may well find that a lot of your existing software no longer runs properly because it wasn't designed for use with Windows XP.

Changing your operating system can cause problems with your drivers - the software that controls components such as your graphics card and soundcard. Upgrading to Windows XP could mean that you end up spending ages downloading all sorts of additional software updates to get everything running properly once more.

The same is true when it comes to upgrading individual programs. If you're happy using older versions of Word and Excel then there really is no need to upgrade them.

This article was written using Word 97 on an old laptop that runs Windows 98. That system works fine, thank you very much, so there's no rush to spend money on new software that's not really needed.

Thanks for the memory
More often than not, the best upgrade you can give an old machine is simply to add some extra memory. All computer software runs better when it's got plenty of Ram to play with and we'd recommend that any PC these days should have at least 256MB of memory, or preferably 512MB. In fact, 1GB of memory isn't out of the question for heavy-duty tasks such as editing full-screen video.

You do have to open up your computer to get at the memory modules on your PC's motherboard, but it's a fairly straightforward procedure. The manuals originally supplied with the PC will help here; these will show you the exact location of the memory modules and should also specify the type of module that you need.

There are lots of different types of memory, with confusing names such as DDR2 PC2-4200, so sometimes the best thing to do is just pop out one of your existing memory modules and take it along to a high-street computer store and show them what you need.

Memory manufacturer Crucial has a handy 'memory advisor' feature on its website to help you to figure out the type of memory you need. Needless to say, Crucial would no doubt like to sell you some memory too, but it does offer good prices, with 256MB upgrades costing as little as £35.

Disk jockeying
Something else to think about is upgrading your computer's hard disk. Video clips, games and music downloads can take up huge amounts of disk space and it doesn't take long to fill a lower capacity hard disk to bursting point.

There are a number of options here. You could simply replace your original hard disk with a new one, but this means starting from scratch and reinstalling all the software, documents and files that were stored on the old hard disk on the new one.

That can take hours so it may be better to install the new hard disk alongside the old one so that there are now two disks sitting inside the PC.

However, doing this can complicate things, as you need to make sure that the new disk is configured as a 'slave', while the original disk remains the 'master'. This can involve a bit of fiddling with switches and cables, so make sure that any hard disk you buy includes a nice, clear manual to help you out.

The most important detail to look out for when buying a new hard disk is storage capacity. For the download fiend, audiophile or video buff we'd recommend buying the biggest hard disk you can afford.

Trust us, it'll fill up soon enough. But if your storage requirements are more modest, you can probably get by quite happily with a 40GB or 60GB hard disk.

The other factor to take into account is the speed of the disk mechanism, which is generally measured in revolutions per minute (rpm). Cheaper disks run at a relatively slow 4,200rpm, although a more common speed is 5,400rpm. You can also get faster (and more expensive) disks that run at 7,200rpm or even 10,000rpm.

However, most home users can get by quite happily with 4200rpm or 5400rpm disk drives. A really top-speed hard disk is only really necessary for work such as professional-level video editing or music recording, which involves constantly pulling enormous files off the hard disk.

Another technical detail to watch out for is the choice between ATA (sometimes also known as IDE) and Serial ATA disk drives. Serial ATA disk drives are faster than ordinary ATA drives, but older PCs may not be able to use them, so remember to check this with the retailer before buying a new drive.

Think outside the box
All this assumes that you're happy to open up your PC and start installing a new disk drive inside. A much simpler option is to buy an external hard disk drive instead.

These sit on your desk and connect to one of the USB or FireWire ports on your PC, so you don't need to open up the case at all. You can get a massive 250GB external hard disk for £200-£250, or a more modest 60GB disk for £125- £150. Internal hard disk drives are cheaper, but we prefer external drives because they're easier to install.

Another way of adding more storage to your PC is to buy an optical drive, such as a CD or DVD writer. Most computers made in the past couple of years already have one built in, but they're a very handy upgrade for older PCs.

Blank CDs and DVDs are pretty cheap these days, so they provide a low-cost way of storing files. And, of course, they allow you to create your own audio CDs and video DVDs as well.

Like external hard disk drives, it is also possible to hook up an external CD or DVD drive using one of the USB ports on your PC. It's worth noting, though, that newer PCs will have the latest type of USB port, known as USB2, which is almost 10 times faster than the original USB1 ports found on older PCs.

Again, your PC's manual should tell you what type of USB port you've got, or you can look it up on the manufacturer's website.

A USB2 device, such as an external hard disk, can still be connected to an older USB port but the slower speed of the old USB port will act as a bottleneck that prevents the disk from running at full speed.

Fortunately, it's fairly easy to install a USB2 upgrade card that will give your PC two or more high-speed USB2 ports. Companies such as Belkin and Adaptec sell these upgrade cards for about £50, and they're a very worthwhile upgrade as they allow you to use all the latest USB2 peripherals.

This is an ideal upgrade for old PCs that don't have any USB ports at all. Watch out if you've got one of these really old machines, though, as older versions of Windows, such as Windows 98, can be a bit temperamental about working with USB devices. Before buying a USB2 upgrade card you should check that it will work with your existing version of Windows.

If you have a digital video camera you will definitely need a FireWire interface to connect it to your PC. You can kill two birds with one stone by buying a product such as Belkin's handy combo card, which provides USB2 and FireWire interfaces on a single card for £45.