Since you're not buying for 2 more months, people picking parts based on combos and price doesn't make sense at this point. Nailing down the types of components you want can be done, but opportunities for different manufactures will for sure creep in the next 60 days. When building a gaming system, its all about balance. I start with what size monitor am I going to be playing on. That drives the GPU, which drives the PSU. Then a CPU that won't bottleneck the games, a quality mobo for OC and a good aftermarket heat sink fan, or any mobo and stock fan works if not OCing. Ram with good timings to match the mobo. A HDD big enough for your needs and the OS to boot. Also upgradability can direct some decisions too. If you want to add a second GPU later, you'll have to get a mobo that can support 2 and a PSU big enough for both. Following that flow, here's a general idea of what you'll be looking at.
1680x1050 monitor ~$150 1920x1080 ~180-200
GPU: 4850 for around $100 or for around $140-$150 GTX 260 or ATI 4870.
PSU: QUALITY 500w+ with good 12v amps ~$60-75 or 600w+ ~100 for crossfire
CPU: AMD x3 $120 or if a great combo is available, an x4 may be possible
Mobo: If overclocking, Gigabyte and Asus are probably where you're going to look. If you don't want to crossfire ATI cards or choose a nvidia card, the 770 chipset is a good deal around $80. If you want the option, then a 790gx is probably where you'll end up at ~100-125.
HSF: (Only if OCing) ~25-50
Ram: DDR3 makes more sense for the future but will cost ~$70. DDR2 will be around $50.
HDD: if you don't need much space, $50, if you want 500+ gb, then $75-$90
OS: Vista with Win 7 upgrade $110
You're case of choice: ~$120
So it looks like you'll be close to budget without any of the upgrades listed here too. If there's extra, load up on the lights. But that will give you a better idea of what you're looking for. Or this won't help a lick and I get one more post count out of it 😛