Here's what I'm running, and keep in mind it's not a dedicated machine, it's running my cab remotely. I just "duplicate screens" when I want to work, then "extend" when I want to play.
I5 2400k, 3.1, 3.3 turbo
16g ddr3
GT 220 1g ddr3 video card
3 angels is no problem, the only games that have ANY percievable stutter are PD's Tron and T3. I do plan to do the graphics card as I'm running all 3 screens from one card, but can't afford to do it at this time.