I'm sorry, I've asked this before, but one thing I still dont understand with it. I know it will run faster if you install Windows twice, once for the VM and once for Boot Camp. But, if I do that will I need twice the space for windows? So instead of taking up just however much space windows XP does, it will take x2 as much because I am installing it twice? Or would installing it as a VM allow me to run it on Boot Camp with a dynamic resizing (which would be amazing...) Thanks again!
It doesn't run faster if you install it twice. I think you're just misunderstanding.
Boot Camp is a utility that preps your computer for having another operating system besides OS X installed simultaneously on your computer. Once the Boot Camp assistant has done it's job (separating your hard drive into two chunks, one for Windows and one for OS X), it's done. Windows will then occupy its own space and OS X will occupy the other.
The advantage to running Boot Camp is that Windows runs natively on your computer. This means that it takes full advantage of your hardware, including your video card, just as though it were running on any other PC hardware.
When you run Windows via Parallels (or VMWare Fusion), it is running in a "virtual machine", meaning that the hardware itself is not being banged on directly. That gives you a little more flexibility in that you are not using the actual hard disk inside the computer - instead, you're using a hard disk file under emulation. So, the file can be dynamically resized. The disadvantage of running Windows in a VM is that some hardware specific features (like your video card's 3D support) are not directly accessible as they would be when you run Windows natively.
You can run Windows however you like. I choose to run two installations of it - one under Boot Camp so that I can play games. The other in Parallels for flexibility and "instant-on" access for the occasions that I just need Windows for a second to do something quickly and then I can shut it down.
Does that make a little more sense?