need a cheap 3d card to run Aero desktop

Just about any card with at least 128MB and hardware acceleration. I put an older 9600se in my parents build and it runs aero pretty well.

Might aswell get the 2400pro..

For Nvidia anything in the Geforce FX series will run Aero.
For ATI anything in the Radeon 9xxx series will run Aero.

It'd be hard to find a graphics card nowadays that couldn't run Aero.

Looks like the best compatible choice would be the HD2600pro or the HD2400XT for that price but not sure where you can buy them.
http://www.sapphiretech.com/us/pro [...] php?pcat=3

i'd personally get a 1650pro agp, dirt chep and do the job.

http://www.diamondmm.com/2400PRO256A.php

PS, edit: ** Ah forget it, this is an AGP card, HyperMemory and TurboCache have nothing to do with it. And AGP Aperture size won't matter here.**

.....

Don't worry about Hypermemory or TurboCache, it doesn't steal memory, it's like AGP Aperture it set aside a dynamic portion from 0 to it's max (some cards can access 1+GB), but it only uses it when need and when the drivers think the need outwighs the system using that chunk. It's very effective, and compared to using HD space or simply baulking, it's good to have. But for just running Aero, I doubt any card would go to HM or TC for large amount of resources. The only one that might even access it would be the rare 64MB GF6200s and X300s, and then it would likely be just another 64MB if that.

I'd say get at least 128MB, but I wouldn't worry about HM and TC in general, the performance difference will be nada for this type of app. Gaming though is a completely different story.