I LOVE Civilization IV, however it appears to require much more processing power than Civ III. I have plenty of RAM, good processor and great video card, but can only really play at the lower video settings. That's not a big deal, though. It still looks great at the lowest settings. (At the highest, a single unit turns into multiple units, which is totally unecessary anyway ... it's just eye candy.) There have been lots of tweaks to the game play to keep it lively ... the element of Religion is much more important now ... culture in general is more useful, and trading with other Civs is easier. Unfortunately the Civilopedia isn't as good, but that's fairly minor. I've never experienced any bugs at all. I've only applied whatever the most recent patch is.