I'll be buying a MacBook Pro 15" at the end of October. However, I'm not sure whether to get the i5 or the i7. What I'm planning on doing is using it for iMovie, Final Cut Express, etc; nothing too intensive. I would personally like to get the i5, as it is about $400 cheaper (I'm in South Korea, if that helps any), than the i7. If I buy the i5, and upgrade it to 8GB of RAM, will it be good enough? Thanks for your help!