You’d be surprised if your new car couldn’t do more than 50mph after a few months.

And what if your new dishwasher took all day to wash a few plates? You’d probably be complaining loudly to the supplier.

But we take it as read that personal computers slow down over time. Unlike cars or appliances, complaining won’t get you very far. But this feature will. We’ve compiled a list of steps you can take to restore the pristine performance of your PC.

With two exceptions, we won’t be looking at hardware purchases, and where possible we’ll be considering free or cheap software to maximise your PC’s potential.

Above all we’ll be looking at ways you can tweak Windows Vista and XP yourself. Unless otherwise stated, all the software mentioned in this feature can be found on our website.

Finally, to avoid repeating ourselves, all references to Vista’s Control Panel refer to the Classic View, which you enable by clicking on ‘Classic View’ from Control Panel Home.

Hardware updates
If you could do one physical favour to your PC, it would probably be to install more memory. In a worst-case scenario, where you have to discard the existing memory modules, an upgrade to 2GB can be bought for well under £100 for a desktop PC.

Although all versions of Vista will run, or perhaps more accurately, jog in 512MB of Ram, if you want the full benefits of Vista including Superfetch and the Aero interface, then 2GB is desirable. XP can also benefit from a memory boost. Although it will run in as little as 128MB, 512MB should be considered a more realistic figure.

In either version, if you are using memory-intensive applications, such as editing large image, sound or video files, more is better. 32-bit versions of both XP and Vista will address up to 4GB (but see our website to find out how devices can use up some of your available memory).

Disk hygiene
Junk files on your PC don’t just waste valuable disk space: they slow down performance, especially on a disk that’s nearly full. On an ideal hard disk, every file would occupy its own physically contiguous sector.

In practice, this state of affairs rarely, if ever, occurs ­ most files are ‘fragmented’, so that the read/write head of the disk has to dash back and forth reading different sectors to load a file into memory. Similarly, if disk writes have to seek out multiple small free spaces to store a file, performance drops.

Disk optimisation is a three-stage process. First you need to check each drive for errors. The procedure is the same in XP and Vista ­ right-click on the drive you want to check, choose Properties, turn to the Tools tab and click the ‘Check now’ button.

Make sure at least the first option (Automatically fix...) is checked or nothing will be repaired. Click the Start button and you will most probably be presented with a dialogue explaining that Windows can’t check the disk while it’s in use, so click the Schedule disk check button to perform the check on the next reboot. The check may take some time, so wait until you take a break before restarting.

Next, perform a disk clean-up. Vista users can once again find this in Performance Information and Tools, while XP users will find it under System Tools in the Start menu. In either case you are prompted to choose a drive and you’ll be presented with a list of what can be cleaned up, such as Temporary files, old Restore points and ‘lost chains’ recovered by disk checking.

Vista has a few more options, such as Dump files, Error report files and cleaning the Hibernation file.