Man of Honour
Get an iMac then? Core2Duo is more than enough for what you need.
I get 50fps on my macbook pro, I get 280fps on a quad core 3Ghz machine under linux. Thats the difference between an hour and 10 minutes which for me is the difference between practical or not.
Sure a brand new imac will be faster than my macbook pro but not that much faster. Obviously a q6600 would be slower than my 3Ghz quad core, so we'll say it does 200fps (I think it'll do better but lets be conservative). If a imac is twice as fast as my macbook pro (which is probably optimistic) then it does 100fps...still twice as long to encode.
Also, I design enterprise and ISP systems for a living, I have a pretty good understanding of what my requirements are and a core 2 duo doesn't meet them.