Richard,
On the registration form, maybe you should ask for ICC username, instead of ICC rating. Then you can grab the ICC rating anytime you want for comparison studies with Chess Tempo rating. Right now you only get the ICC rating at one point in time, when the person first joins Chess Tempo. (And it should be ICC, not ICS. ICS ended on March 1, 1995

By the way, ICC has rating graphs for Standard and Blitz for all usernames. Maybe you can do comparision graphs with Chess Tempo ratings sometime when you have extra time, which might be never
