Now-a-days, most of the systems, either they are laptop or desktop, come with pre-installed Windows Vista. Though Vista has got its own advantages but the biggest disadvantage is that it does not support all drivers and softwares. That is why we often need to have Windows XP on our PCs and Laptops. Now there are 2 ways of doing that.

Keep Vista, Install XP and create a Double Boot (Recommended)
Remove Vista and have a clean Install of XP

Now, both the options have pros and cons, I will not get into them …