I'm not sure exactly what you need. . . I mean really need. . . but we are editing our second feature using PP CS5.5 using a THREE YEAR OLD Macbook Pro using daisy-chained Firewire 800 drives. And it works! I get real-time playback at 1/16th resolution, which is all we need for editing, and I can output pretty much anything using PP.
Now, we do not do our own color work, so that might be an issue with you, but for strictly editing, you'll be fine with pretty much anything. PP CS5.5 is an amazing program!
Hi Stephen, see I here this and I am once again tempted to go with a macbook pro for now...if you can get 1/16th real time on a 3 year old laptop, I feel like a brand new quad core macbook pro with thunderbolt RAID drives should be able to edit pretty decently at 1/4 realtime, and maybe have to do some rendering for color correction playback, but honestly, my current computer usually needs to do rendering for my color correction anyway