So I'm looking into a new iMac and my budget is 1500 so I'm wonder whether to get the 2.5 ghz and get some ram from OWC or just go with the 2.7 ghz please help me decide
How long do you intend to keep the machine? Because you can always save up more and buy RAM later, but the processor is pretty much set. For this reason, I would recommend getting the 2.7.
Since you'll be spending $300 more for the 2.7, you're also getting twice the hard drive space and a better graphics card.