Whether you want to run XP mode on your Windows 7 machine and you can't for lack of a chip that supports virtualisation or you just don't want to use Microsoft's virtualisation software, you can run XP mode sans virtualisation.
Over at How-To Geek they've put together a guide to running XP mode without jumping through all the Microsoft-approved hoops. You'll need to download XP Mode from Microsoft (but skip the part where you download Virtual PC) and grab a copy of the free VMware Player. XP Mode can be imported directly into VMware Player and can even be linked into your main operating system (for sharing files and internet access) through VMware Tools.
The guide at How-To Geek provides picture-heavy step-by-step instructions so even if you've never used a virtual machine application before, you shouldn't have any problems getting started with VMware player.
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