New Macbook Pro and Photoshop CS (Old Version)

Hi. I may be getting a new macbook pro 15" 2.2, 2gb, but I'm concerned about a compatibility issue with the oldest version of photoshop CS. My employers are cheap and will not upgrade of CS2/CS3. They are the spend a dime to save a penny type of place. They have photoshop 5.5, 7, and the old version of CS available for me to use on a new laptop. I'm currently running the older version of CS on my Powerbook G4 and it works fine. I'm worried though that it will not work with a new Macbook Pro. Does anyone have old CS working on a new Macbook Pro? How well does it work? Thanks.