Rig Critique Please

I am currently editing DSLR footage on a laptop and now have about $2500 to spend on a modest HD editing rig. I would like to edit the DNxHD codec in real time (preview) in CS4 (CS5 soon). This is the setup I am looking at building;
1. AMD 1090t - CPU
2. Asus Crosshair IV - MOBO
3. 8gb Ram
4. Radeon 5850 - GPU
5. (2) 2TB HDD - Storage
6. HAF 932 - Case
7. LG Black Bluray burner
8. Win7 64bit
9. (2) monitors

I am unsure what boot drive to get and I will be editing on the 2 monitors (1920x1080) and a 50" Plasma TV "client monitor". If I can save money somewhere, let me know. Is the 5850 overkill for editing HD?
Thank you so much for any assistance.