Make use of virtualisation

Virtualisation does need an awful lot of computing horsepower, and virtual PCs need just as much memory as an ordinary PC, so we’d recommend a reasonably modern system (at least a Pentium 4) and as much memory as possible ­ – 1GB as a minimum but 2GB is better.

Virtualisation software
The two free virtualisation options we’d recommend for those just starting out with virtualisation are Microsoft’s Virtual PC 2007 and Sun’s Virtualbox. Of the two, Virtualbox is the most fully featured and can be run on a much wider range of host operating systems (the host OS is the one running on the real PC, the guest OS is the one running inside the virtual PC), and for this reason we’re going to concentrate on Virtualbox.

Download Virtualbox from the Sun website and run the installation program, which is a Microsoft installer package (.msi). If you’re running a third-party desktop firewall, you may get prompts about allowing Virtualbox’s virtual network adapters access to the internet. If you want your virtual PCs to have network and internet access, allow all the requested changes. Setup should complete pretty quickly, and now you’re ready to create your first virtual PC.

Creating a virtual hard disk
When you first launch Virtualbox, you’ll be asked to register a name and email address. You can opt out of any contact by checking the box on the sign-up screen. Continue to the main interface and hit the New button.

This starts a wizard that will let you create your first virtual PC. On the second screen, give your virtual machine a name and choose the OS you want to install on it from the dropdown box. As you’ll see, there’s a vast range to choose from, but don’t worry if yours isn’t listed, as all this selection does is work out the minimum amount of Ram you’ll need ­ – you can change this setting in the next screen anyway.

Although your PC is virtual, it still needs real memory to run in, so make sure you have plenty of Ram to spare. We’d recommend allocating at least 512MB to any virtual PC if you have 1GB installed, or 1GB if you’ve 2GB on your host PC.

Once you have set up the memory, you’ll be asked to choose a virtual hard disk for the virtual PC. Again, by hitting ‘New’ a wizard will guide you through the process. You should bear in mind the requirements of the OS you’re going to install, but 5-10GB should be enough for most Windows installations. You can create as many virtual hard disks as you wish in almost any location on your host PC, for use with different virtual PCs.

When you launch the virtual hard disk wizard, you’ll see that you can specify either a fixed disk size or a dynamically expanding one. This latter is a great space saver, as it only uses as much space as is required by the virtual OS. So a 10GB drive might start off as 1GB in size, only growing as you add applications and files to your virtual PC.