game freezes after about 10 or 15 minutes

[macro]

only thing i can suggest is update to win 7 and see what happens. if your computer cant run it then its time to upgrade. couple of questions though:

what settings in video options do you use?
how much memory does that vid card have?

i used to have a similar set up to that but with a better video card. got mine to run but at low frames and slideshows in busy environments (alot of fighting going on) so i upgraded