Hi there!
First post here. I'm a Model e2 User since march (from Austria).
I've tested quite a lot of Games on this gadget, and it's not always easy due to it's native screen resolution. But with a little trial and error quite a lot of games run perfektly on the OQO.
Games perfectly playable on my OQO (I'm using XP of course):
C&C - Tiberian Dawn (640x480)
C&C - Red Alert (800x480)
C&C - Tiberian Sun (800x480)
C&C - Red alert 2 (640x480)
Civ 1 (Fullscreen)
Civ 2 (800x480)
Colonization for Windows
Imperialism 1 + 2
All the Scumm-VM-Games (fullscreen)
Starcraft (640x480)
Tropico (640x480)
Worms World Party (640x480)
Anstoss 3 (Football Management Game)
Trackmania Nations forever
and many more of the older games.
And there are a lot games with minimum screen resolution 800x600. So there is a need to scroll - this is quite annoying with some games but with some others ist's still fun. These are:
Alpha Centauri
Civ 3 (Native Resolution needed is 1024x768 - not playable. But there's a little tool which makes it possible to play on 800x600. I#m verry happy with that.
Gettysburg! (Yes, I'm a fan of Sid Meier Games

)
Age of Empires 2
Medieval - Total war
I've never tested games in windowed mode so far.