I'm lucky enough to have tried all of the options available. Used to work in high end Hi Fi and AV so got to play with a $25,000 projecter on a 20' screen, also a 32" pioneer with 1.1 pixel ratio and 5ms delay a 19" widescreen with a fresnel lens and now 3 x 24" Dells. I could not go back to one monitor, it's not screen size it's how many pixels you can push, so I compromised on graphics for resolution as long as I can see where the track goes and where the car behind is, it's all good. I'm usually to busy to worry about how pretty it looks. The projector was fun but for immersion you can't beat a triple screen set up.
Running a E8600 C2Duo O/C to 4.25 Ghz, 4Gb RAM and an ATI 5970 @ 5960x1080. My only regret is not getting 16:10 monitors as a bit more headroom would be nice. I'm capped on iracing to 120FPS and in rFactor I get from 80 - 240 dependant on track and mod.