I'm in the market to build a super budget (around $600) gaming machine to get me started back into PC gaming. I'm looking to build a system that I will be able to upgrade in the future as components become cheaper, but that will still allow me to play games with decent settings (Orange Box, Savage 2, etc). I'm not planning on OC-ing or running SLI and I realize that I'll probably have to upgrade the GPU first, followed by the CPU/MB. I already have a 22" Samsung 226BW, XP, Mouse/keyboard, speakers, etc.
I think if you can spare the money, DO NOT get the 8600 gt, 9600 gt was just released today and according to the reviews, the 9600 should spank the 8600. However, it is about 170-180. But I think you would be happier, or look at the ATI radeon 3850, those are a decent buy as well.
Since you say you want upgradeability, you need to be looking at AM2+, so that way you can have an AM2 chip, but also have the capability to go to the Phenom down the line, whenever they get it fixed.
How about this for case? Free shipping, gives you the Earthwatts PSU with it. Looks good for your price, but I think I'd upgrade to a better video card if I were you. Do you have an OS and all that?
It's the graphics card that will be the worst part of it here. An 8600GT is pretty weak by current standards. If you are really on a budget but think you can get money within 90 days of purchase, get an EVGA 8600GT and use their step-up program when you get a bit more cash to step-up to an 8800GT or 9600GT. If you can afford to go up to an HD 3850/3870, 8800GT or 9600GT I would highly recommend doing that and trying to overclock your CPU, it isn't hard to overclock and can get you some performance gain.