If you're not a gamer (which it doesn't seem like you are) then I'd go with an NVIDIA 64mb card minimum, I have an NVIDIA Geforce FX5200 that's 128mb, works great for me.
I've used an NVIDIA Geforce2 MX 400 64mb and it worked fine also.
I can tell you what kind of memory you can have if you do this:
Download Everest Home at
|MG| EVEREST Free Edition 2.20
Install & run it, once it loads click on "Motherboard" then click on "Motherboard" again and post what it says for "Motherboard name"