Great! I think it's probably going to be hard to get much higher on a 256MB card. If you need to go much higher than that you'll probably need a 512MB card to do it.
> Maybe Michael could implement something internal so that
> the MOI screens itself need less graphic memory.
Actually, I've already done quite a bit of work on that, which is why MoI works so well on a machine with only 32MB of video memory (see this old thread for when that was improved: http://moi3d.com/forum/index.php?webtag=MOI&msg=322.6)
About the only thing left to do would be to temporarily turn off the display completely...
In general if you want to go really high resolution I would recommend having a video card with a larger amount of video memory on it.