My main purpose is gaming but I don't really ever do more than one thing at a time (unless having Facebook or google or something up while playing a game). With that said I know for sure my Quad is an "Intel Core 2 Quad CPU Q8200 @2.33 GHz 2.33Ghz" but as for the other one I'm not sure. I know it is a Duo Processor and it could be anywhere from 2.66-2.99 GHz. I only stated 2.66 to show the minimal. The reason I ask is not because I would be replacing my quad with the duo but I'm using my family PC which has the Quad and I am possibly getting my own PC which would come with the duo and want to know what to expect from it.
For some games that use more than 2 cores the quad core would be better, burt for games that dont the faster clock speed dual core would be better. The quad core would be the better overall processor though.