In the third part of my Windows Vista review, I examine your various options for installing Windows Vista, and run through the clean install process, comparing it to that of Windows XP. Dual-boot. If you're not sure how well Vista is going to work on your existing hardware, consider dual-booting between Windows Vista and your current OS. This method will provide you with a boot menu when you turn on your PC, letting you choose each time which system to use. Dual-boot is a great method of evaluating Windows Vista, but it comes with some complications. You must have an empty hard drive (or partition) to which you will install Windows Vista; you can't install two or more versions of Windows in a single partition. If you only have one partition, it's possible to resize it to accommodate the create of a new partition, but you'll need a special tool for that. What you're looking for is a non-destructive partitioning utility. I typically use PartionMagic, but there are other solutions out there as well.

Paul Thurrott Windows SuperSite