You can't use bootcamp in parallels. Parallels is an application that allows you to install windows "inside" of Mac osX, but then uses RAM and other system resources to run it, that takes away from Mac OSX. Bootcamp, on the other hand, partitions your hard drive so that you can either boot into mac osx or windows at startup by holding alt when you see the all grey screen. This runs the two operating systems separately, and not together, where as with parallels, you run both at the same time. Bootcamp comes with OSX, and parallels you have to buy. Most say that Bootcamp is better for gaming, while parallels is good if you don't want to reboot every time you want to switch operating systems. I use bootcamp and it runs XP very well on my Late 2008 aluminum MacBook. But I have also heard really great reviews for parallels as well. It really depends on your needs.
Quote at least some of this post if you have any questions so I know you have a question. Hope this helped a little.