it is simple... with Mac, you do not need specs... compared to PC where you have to compare each component you have to add, the Mac are always bundled with the most powerful specs when you buy it... you can't buy a old mac that will need upgrades... it is always the up-to-date perfs... if the specs change tonight, in the store tomorrow you will have the updated specs... no lame configs with "possible upgrades" when you send the coupon.. lol
actually, if you have an average use of your computer, the latest iMac can handle it... and for now, you will have a rebate on the next OS that is coming this fall... it is easy to check what you can need:
http://store.apple.com/ check the type you need, and tada! (oh and you can say hello to my iPhone!)