What version do you have?
If you have an earlier one you can just save the DB99 (i think that's right) folder and just put it in your new copy. However, if you're using the newer 2000 versions, I think the procedure is different. I tried to do the same thing upgrading to 2000 but it didn't work. My contacts went goodbye. ICQ has instructions on doing it, I've seen them posted.
Good luck,
joey1412