GTA IV PC game help please?

Look at the minimum and recommended specs and this will give you a better idea. I don't believe its the CPU. I think your RAM is the problem. Can you O.C. the RAM in your BIOS or an on the fly program? I'm almost certain thats gonna be the prob. When you go to get new Check out Corsair.com as thier "Dominator" series are certified/tested to performance I have the "Dominator" PC8500 1066MHz and a native FSB of 1333MHZ but you only have 800MHZ FSB so you'll need to get PC6400 800MHz RAM. I'm almost certain this is your problem and if you only have 32 bit OS then get 3 gigs if 64bit get 4 gigs in the (2x2024) modules