Replying to How much ghz and ram?

Hey guys just looking for a little advice at the moment. I'm thinking about upgrading my computer soon, so I need help with ghz and ram. Basically what I'm looking for is something that can run Adobe Bridge and Photoshop (both CS4 if it makes a difference), a browser and iTunes all at the same time without freezing, glitching etc. What is the minimum of both ghz and ram that i should have? I have a TB hard drive, so hard drive isn't an issue.

Would a Macbook pro with 2GB ram and 2.26 ghz be sufficient? Overkill? or would 4GB and 2.26 be better? I'm not too bright when it comes to what these things mean.