whatr would i need in my pc to make 2 windows os on the same drive and to run pc games lke halo 2, halo,etc?
Well you see you won't be able to run Halo 2 on your PC unless you have Windows Vista, a little tricky since that isn't out yet. To run games like it, I'd recommend a powerful GPU, but I've no idea what you already have, that may be sufficient. To have two versions of windows you need to make another partition, using a partition manager, and then you will have two areas on which to install windows.