RAM, Hard Drives, and DVD Drive
2x G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 - $109.98 ($54.99 each)
Patriot PE32GS25SSDR 2.5" 32GB SATA II Internal Solid state disk (SSD) - $92.99
HITACHI 0A38016 1TB 7200 RPM SATA 3.0Gb/s Hard Drive - $87.99
LITE-ON SATA DVD Burner - $22.99
With Windows 7 on the horizon, and ever more memory intensive applications being released, 8GB of RAM seems to be the current sweet spot for new builds. The great thing is that RAM has never been cheaper, and 8GB of fast DDR2 1066 can be easily found for just a little over $100.
Installing your operating system on a solid state drive can drastically reduce boot times, and make your computer seem much more responsive in general. Unfortunately, until recently, SSDs were extremely expensive, and were only included in the highest-end computers. This Patriot solid state drive combines performance nearly equal to high-end SSDs, with a much lower price.
Of course, you'll also need a place to store all the games that you'll be playing as well, which is why we recommend this 1 Terabyte Hitachi as the main storage drive. It has plenty of space for games, as well as movies, music, and pictures.
We almost added a Blu-ray drive to this build, but decided that they're just too expensive, even at $90, for a pure gaming PC. Down the road, it may be necessary if PC games start to be released on Blu-ray, but for now, a simple DVD burner is just fine. We went with a cheap LITE-ON model with a SATA interface.