that's very normal. Especially after you have edited a number of large jpegs/raws without restarting Photoshop. Not only CS2, CS3 worse. The memory used after some editing is NOT released. You have to restart photoshop once in a while to release them.
Is there an alternative graphics software other than Photoshop? Which can also be used for photo editing. I made A1 panels today and it took me 5 mins or so to save and open.