I've got a 8600M GT 512 DDR2, and it's pretty much perfect for my needs. Although, to be fair, one of my considerations was screen size (15.4" widescreen), and had I picked a desktop, the budget for my laptop could have easily landed me a 8800GT and a nice quad-core

.
I play my games mostly high settings, with Crysis being the notable exception. Its decently fast, but not a screamer; the only way I can really describe it is "fast enough".
To answer the OP:
Setup:
C2D Merom T7100 1.8 Ghz on Santa Rosa
2GB DDR2-667 RAM in Dual-Channel
8600M GT 512 DDR2 (underclocked from reference clocks)
Vista Home Premium x64
Forceware 169.04
Copied from my post on the 8600 Go Thread:
HL2: Maxed settings, full HDR, 16x AF, 6x MSAA, 1280x800. FPS: 70-300 ~ish
HL2:Ep 1. Maxed Settings, Full HDR, 8x AF, 2x MSAA, 1280x800. FPS: 50-70 ~ish
TF2: Maxed Settings, full HDR, 2x AF and no AA, 1280x800 (Mostly because I am a FPS nut on MP games). FPS: 50-70~ish
ET:QW. Maxed Settings, 2x AA and 4x AF, 1280x800. FPS: 45-60+ if unlocked
Guild Wars: Maxed Settings, 4x AA and 8x AF, 1280x800. FPS: Solid 60
UT3: Detail Max except World Detail 4/5, 1024x768. FPS: 45-60+
Crysis DX9- All Med except texture detail high, 1024x768. FPS: 35-55
Crysis DX10- About half and half Med/Low. 1024x768. FPS: 35-50
Far Cry- Maxed out, 2xAA, 1280x800. FPS: 45-60 (?) (All I know is that this was very playable)
FEAR- As far as I could tell, ran well on max settings. Had weird driver issue where FPS tanked after 10 minutes of play, supposedly fixed now but uninstalled and too lazy to check.