Can anyone please explain to me in idiot terms (I'm referring to myself here) the main differences between the i5 and i7 processors? I am getting a new MBP in the near future and am wondering if it is worth the upgrade to the i7? I will be mainly using Aperture 3...I plan on upgrading to the 7200RPM HD as well as 8gig of RAM. I just want to make sure that Aperture runs as smoothly as possible (I've read that it can make a system very sluggish). Thanks in advance!