You can upgrade to Vista. I have a similar system (Pentium 4 3GHz, Radeon 9600/X1050, 1GB RAM DDR400) and it runs perfect. First thing I need to do is grab the SiS AGP Controller driver or it will lock up. Other than that, it runs fine. No slow downs. It's slower than XP, but really...it's normal. Instead of taking 5-10 secs like XP, it takes 9-15 secs for Vista.