You need either a GameShark or a Sharkport. As of right now, i'd say get the sharkport as you can get more use out of it for GT3. but if you like to cheat alot then go with the GameShark.
Although... you can always d/l someone else's savegame whos free'd everything up effectively "cheating" so a sharkport would do nicely as well. its your call
