Worth it for me to pick up GTA IV? AMD X2 6000 Geforce 8600

The way it is now, no. A lot of people with quad core Intel chips and 9800 GT Nvidia cards aren't even able to play it maxed out. Rockstar is apparently working on a patch. Although a lot of problems with slightly lower end cards were driver related I think. Even if you get a high end graphics card, the game is very CPU intensive, so you'd probably have to scale back a lot of effects with an AMD chip handling it all. Nothing against AMD, I think their graphics cards are better for the money, but Intel simply crushes them in the CPU department; especially for gaming.