Questions about XP reinstall

[Joni Nitro]

Well its time for a widows install again. I have done a lot of reformats and installs, but none like this. I am on deployment in Iraq and before I left I loaded up all my games like FarCry, Doom3, Halo, and some others. Now, in order to keep my load a little lighter I cracked my games. I am not sure if that is legal or not, but it is probably not. So I want to do an install of windows in my laptop, becuase it is starting to run like crap. Is there anyway to do this and back up my games so I dont have to have the disks to re install?
I thought about backing up the program files folder and the registry but I am not sure if that would be enough. I did a full back up onto an external HDD, but dont want to get any corrupted windows files back on there. This would also be a good time to upgrade my internal HD. Can anyone help me out?

Also, I have a copy of both XP home and pro, which would you install. Home came with on the isntall cd for my laptop, and pro is one that I bought seperately. Thanks, John