Testing your lovingly crafted web application in Internet Explorer is so much harder than it should be. IE6, IE7, and IE8 all have a healthy market share, yet it’s impossible to test all three versions on a single Windows OS. There are some clever hacks and nifty software, but all are flawed and few run well on Windows Vista or 7. The most reliable testing method is to use three separate PCs.

Few of us have the room or patience to maintain three PCs, so we resort to Virtual Machine software such as VMware or VirtualBox. VM software emulates a PC (the guest) on your real PC (the host). Assuming VM software is available for your host operating system, you can run any other OS within a VM. In most cases, a VM is just a file containing a hard disk image. Therefore, VMs can be backed up, cloned, or moved far easier than a real PC.

Microsoft Windows Virtual PC and XP Mode Virtual PC is Microsoft’s alternative to VMware and VirtualBox. It’s available as a free download for most versions of Windows. As a standalone product, it’s functional but offers fewer facilities than the competition. However, XP Mode is Virtual PC’s killer feature. It provides: a fully licensed, stripped-down, virtual copy of Windows XP SP3.

a clever facility which integrates the guest Windows XP OS with your Windows 7 host. In effect, you can run XP applications as if they were native Windows 7 programs. Although the XP application is isolated, it can still access the host’s files and systems. This benefit to web developers is obvious: you can run real versions of IE6, IE7, and IE8 on the same desktop at the same time without any conflicts.

Installing Virtual PC and XP Mode Before going any further, you should check which version of Windows you’re running: Windows 7 Professional, Enterprise, and Ultimate users can install Virtual PC and XP Mode.

Windows 7 Home users can install Virtual PC, but you’ll need your own XP installation disks, and you’ll be without the benefits of XP Mode integration.

Windows Vista and XP users can install the older Virtual PC 2007. If your system lacks support XP Mode, I would recommend VirtualBox rather than Virtual PC. It’s free (open source), faster, and offers more facilities. Assuming you’re still here (and not off installing VirtualBox), follow the steps below to install Virtual PC and XP Mode: First, check your PC’s compatibility. To run XP Mode effectively, I’d recommend at least 2GB of RAM. It’ll probably work with less, but it will be more of a chore to use. XP Mode requires hardware-assisted virtualization (HAV). This is supported by most modern processors, but it may need to be enabled in your BIOS. The BIOS menu is normally accessed by pressing Del, F2, or Esc immediately after switching on your PC. Microsoft also provide a useful HAV detection tool which can help you with BIOS configuration. Next, download XP Mode and Virtual PC. The downloads are available from the Microsoft Virtual PC page. After selecting your Windows 7 OS version and language, you’ll be presented with two download links: Windows XP Mode

Windows Virtual PC Download and virus-scan both files before proceeding to the next step. You must install XP Mode first! I realize this seems a little odd, but it’s what you need to do. Once it’s complete, install Virtual PC and reboot your PC.