CS 1 Works totally fine here on 10.6.8 and Rosetta is a killer feature, very fast and unobtrusive, I generally don't notice speed differences between CS1 (PPC) and CS5.5 (Intel) on the same machine for normal size files. So I have no reason to believe this won't be the case with CS2 as well. With gigantic files 5.5 certainly has the edge as it can use way more memory.
Don't forget to ENABLE rosetta on 10.6. It is no longer ON by default.