CPU: i5 750, $200
Mobo: ASUS P7P55D, $150
Ram: G.SKILL Ripjaws 2 x 2GB, $80
HDD: WD Black 1TB, $110
PSU: Antec EarthWatts 650w, $80
Case: up to you
As for the GPU, i would recommend 3 different cards: Ati 4890, Ati 5770, and nVidia 260. The 4890 is $195 and the fastest card, the 260 is $205 and second fastest, and the 5770 is $165 and the slowest right now. Seeing as how the 4890 is cheaper and faster in almost every game compared to the 260, i'd say its a no-brainer. The 260 is faster than the 5770, but so expensive that i dont think you'll hit your $900 budget after case. The 5770 is the cheapest, but has dx 11, and as drivers improve, so will performance.
(EDIT: added PSU, links, and updated pricing)
Mobo: ASUS P7P55D, $150
Ram: G.SKILL Ripjaws 2 x 2GB, $80
HDD: WD Black 1TB, $110
PSU: Antec EarthWatts 650w, $80
Case: up to you
As for the GPU, i would recommend 3 different cards: Ati 4890, Ati 5770, and nVidia 260. The 4890 is $195 and the fastest card, the 260 is $205 and second fastest, and the 5770 is $165 and the slowest right now. Seeing as how the 4890 is cheaper and faster in almost every game compared to the 260, i'd say its a no-brainer. The 260 is faster than the 5770, but so expensive that i dont think you'll hit your $900 budget after case. The 5770 is the cheapest, but has dx 11, and as drivers improve, so will performance.
(EDIT: added PSU, links, and updated pricing)