I have a 64 MB card (Geforce 2 MX400) and here are some of the many problems I have:
* I have to use the smalleest render shroud because the software is very sluggish as my card struggles to render everything.
* I have yet to actually get 30 FPS or higher on any level. Usually around 27 and fully playable, but still.
* cannot see ANY shader effects.
* cannot see ANY lighting effects (only ambient lighting and adjusting it has no appreciable effect on my card)
* I've seen some weird clipping effects (zombies arms going into walls, etc.) , but am waiting until I try a higher crd before I try to report them as actual bugs
My advice is do not even attempt to try and run it with a 32MB card as you will likely be VERY dissapointed by the speed and lack of features ;(
If you can afford it or convince someone to buy it for you try a new graphics card from Newegg.com. They have many from $50 - $100 that would probably do the trick for you (be sure that you are selecting the right kind for your system PCI, AGP, AGP8 etc. etc.)
Good luck!