Not to sound like a fanboy (which I'm not btw), but we have to give Firaxis credit for what they've done with the Civ series. Sure there are issues, I have a ATI card myself so I know first hand the frustration of the game hanging and locking up, but overall, this is a very satisfying game to play and I for one am not sorry a bit for having purchased the game. I will be upgrading my system in about 3 months and by that time, I sure hope that an expansion pack is either available or well on its way. I'd love to have more units and certainly at least 30 or so Civs to play against.
All I'm saying is give Firaxis a chance. They'll patch the game up sooner than later, and I'm excited about the upcoming SDK. Can't wait for improvements to the AI, which among other things, will be one of the many things possible with the SDK.
We should have a We Love Firaxis Day