If you are thinking that this won't have any effect in the long run, allow me to politely disagree. In my country, every 11-year-old child recently acquired a free netbook with Ubuntu pre-installed (on most of them at least). Pretty much each one of those lads (and ladies) I have spoken with likes Ubuntu more than their WinXP installations - and pretty much all of them run WinXP anyway, because "games don't work on Ubuntu".
Some of them have discovered the Ubuntu Software Center and started installing games from there (I was mightily surprised when I saw my cousin playing bzflag on an impromptu lan party!) but that's still not enough: no Starcraft, no Counterstrike, no Unreal Tournament (all of those run but are far too slow to be playable on Wine - plus, Wine is far too difficult to setup).
My point? Add a few quality games to Ubuntu and people *will* come. That's all.