I recently purchased the RAIDMAX SMILODON case with 500W power supply when it was heavily on sale. I've heard the power supply has a tendency to suck, so I might have to upgrade that too.
Ideally, I would like to start with CPU/Mobo/Memory/HD/DVDRW and work on integrated graphics until my next paycheck, when I will buy the videocard (and new power supply, depending on the card and my experience so far with the included one). This method would allow me to spend a little more money (~$550 on the above purchase), then maybe ~$150 on the videocard (plus whatever the new power supply costs). If I had to buy the videocard with the above components, I might have to drop the total amount I'm willing to spend to $600.
Graphics: This I'm kind of clueless about...Should I just buy a nicer card, or get the crossfire/sli mobo above and get two mid-end cards? I want to spend ~$150 ($125-175 is fine). If I get one card, do I need a new power supply (see above post)? I'm guessing I might need a new PSU if I went with a crossfire build...
Heatsink: same as above, mostly clueless...can someone find a good one on newegg?
DVD/CD: I have an IDE DVDRW, but would it be worth the $30 to get a new SATA one?
Now here the problem, you want to purchase the video card seperately, which is fine, but this build does not have integrated graphics. The HD4870 1GB is a great choice for you, but its ~$150.00. You could get something like a HD4350 to hold you off until you buy the nicer GPU (Cheap temporary option), or go ahead and spend the money and get everything now. I would never use that PSU you have, and would probably just throw it away, it only stands the chance to ruin this new hardware you are adding.
Any decent aftermarket cooler will use a backplate and screws instead of the push-pins. That means you have to remove the motherboard to install the HSF. I would buy the cooler now if you think you're going to want to overclock (and who wouldn't want to overclock since it's so easy with the new CPUs?)