World of Warcraft plays very smoothly on my eo i7210. In fact, I was surprised to find that it plays just as smoothly on my i7210 as it does on my high-end Alienware laptop. I use a ThinkOutside bluetooth keyboard, which folds small enough to easily fit in a pants pocket.
I initially had graphics problems with most games I tried on my eo (e.g., Jagged Alliance 2 and MS's Pool for UMPCs). I tracked the problems to the Touchkit touchscreen utility that came installed on the i7210. I haven't had a single problem with games since I uninstalled Touchkit.
FWIW, I find that if my eo (1MHz processor and 1MB of RAM) meets the minimum requirements for a game it will run it. Also, I've had no problems whatever playing games on Pogo and other on-line gaming sites with my UMPC.
Tom