(sorry for the double post =/ )
MacBook Pro (early 2008)
Mac OS X 10.5.5
2.5 GHz Core 2 Duo
4 GB RAM
nvidia 8600M GT, 512 MB VRAM
CX Games 7.1.1
Running TF2 in windowed mode, 1600x1000
These were problems I encountered without messing with GLSL in the reg or DX levels:
-Black textures (whole people/only faces/seemingly random would be all black)
-Invisible weapons (sometimes the weapon I was holding would be invisible...I could still use it but I just couldn't see it. Mainly occurred on class selection and item/character info screens)
-Scroll wheel didn't function normally
-Character's faces didn't have expressions or speak
-Voice chat seemed to lag when I was speaking
-Ubercharged people didn't have the 'shiny' effect (probably because of the lack of DX9)
It never crashed on me, and despite all of that, it was still playable. Not great, but certainly playable.
I then fooled around with enabling GLSL and doing dxlevel 90, which took away a lot of text and made characters unusually shiny.
Since that didn't really work too well, I reset it to dxlevel 81 but kept GLSL on in the registry.
...and to my amazement, the black/invisible textures were gone, and characters spoke and had expressions and stuff.
However, 10 minutes into my first game, it crashed to Steam for the first time. I reloaded it and played for another 30 or so just fine. The scroll wheel issue was still present, though.
I can go into more detail if you want, but there ya go, hope it helps. I'd be willing to run some test/configs/CPU monitors if you want.