Boot Camp is the first thing that come to people’s mind when they need to use Windows on the Intel Macs…but what if you want to use your Windows Programs inside your Mac OS? You could use applications like Parallels Desktop and VMware Fusion. Parallels Desktop has a longer history than Fusion, while Fusion is backed by VMware, which has a long history of making Virtual Appliances.
If you wan a summary of the article above, you can take a look at MacNN’s article: http://www.macnn.com/articles/07/12/19/vm.test/
Here is MacNN’s short summary:
Parallels faster for XP, Fusion for Vista.