If you need to run in a window then I see a problem already. Games running on a TripleHead2Go don't need to be run in a window. Many games can't be run in a window.
yes i know, but all the games i've tried do. Turns out that you dont even need to span the monitors in the driver on my x800pro. I could just span the window and doom 3, serious sam 2, WoW are the games i care about and they ran flawlessly. However i do see the point that you can't tell the driver to span one sized screed with another. It assumes that both screens are the same size.
If you are willing to run your games in windowed mode, this is a liable option, however for me i think i'm just going with the triple head sence i will eventually end up with sli and sli doesn't like more than one monitor.