There's a difference between the iMacs and MacMinis. To begin with the iMac runs on Core 2 Duo. The MacMini's on Core Duo - but if you're using it mainly for word processing (btw, you can always choose NOT to use Office for Mac, but use Open Office or NeoOffice) a Core Duo should be more than sufficient

Go visit the stores and check it out - most of them are pretty helpful but be sure you're speaking to someone who's well versed to advise you and not merely some salesperson *g* The other thing u need to really check is if the game you usually play (Sims) is 'playable' on a Mac cause from what I read, hard core gamers should stick to Microsoft