How much graphics memory do I need?

[peter.marks]

What graphics card would you use for large desktop real estate with many simultaneous apps under Ubuntu and Compiz?

I'm putting together a software development machine with 2 X 1920 X 1200 displays. I don't do any OpenGL development work, but I think that UI's over the next couple of years will use compositing engines and thus demand more from the graphics card than the current generation of desktop apps. I'll also be running Windows in a VM.

I'm thinking about a 7900 GS, GT, or GTX. However I have no idea what sort of memory demands my usage will place on the card. I know there was a problem with windows going black in Compiz due to poor memory usage in the nVidia driver, but I believe that has been fixed now.

[poene]

I don't think you need anymore than a 7900 GS because you did not say you wanted to play games, but you can safely use anything with 256MB of RAM for a while. Even if desktops use a little 3-D acceleration, it's not as if you're in a fully 3-D world like in the movie "Hackers". Even a 7300 GS would be suitable.

[dd_dentfull]

I tend to disagree with poene here, and would reccomend you getting as a minimum a geforce 8 series card or a radeon 2K. there's no telling where would the current "composite" desktop eviroment would go and they can get pretty demanding as they are even at much lower rez.
at any rate, I wouldn't recommend running ANYTHiNG composite on a developement enviroment for the time being due to beta status (as in current compiz and variants) or simply shoddiness by design (vista).

[peter.marks]

Thanks for your replies. I went for a second hand 7900 GTO which seems to be doing fine. Took me a while to get the second monitor working (had to go with TwinView rather than dual driver and monitor config), but it seems to be stable now. I'm yet to move all my activity over to this machine from my old Windows box, but I'm pretty happy with it all so far.

[W.Russell]

Nothing more than any of the 7900-series would be necessary for this specific task.