Graphic designer, currently using a 2.4GHz Core2 dual-processor MacBook Pro (2gb RAM). Considering a new i7 quad-core MacBook Pro; I could get either the 2.2Ghz or 2.4Ghz. Would rather save $400 and get the 2.2Ghz. Is this a step down because of clock speed, a step up because double the processors, or apples-to-oranges? Which would you recommend? Either way, I'll load it with 8gb of RAM and opt for a 7200rpm drive. I do graphic design, including editing large photos and running several Adobe CS applications at once, and occasional video editing.

My question: will it make a difference to get the 2.4? Is going from my old 2.4 dual-core to a new 2.2 quad-core a step down, or still a step up, or neither? I'd rather save the money and get the 2.2 if there's not a huge difference. I'm also wondering whether, a year or two from now, I'd wish I'd gone with the slightly faster processor.