At this point, the number of topics seems fine based upon the activity in the forums. If the usage increases it would indicate the need to possibly break up categories or create new ones. It seems like the challenge which every forum (or bulletin board, or online community based service) has is how to get people involved.
Borrowing from the success of other online community sites it seems that the way to get people to use these things is to give them the ability to create their own area (aka My Space, Facebook, LInked In, Plaxo, etc.) Judging by that type of platform, perhaps putting some more emphasis on profiles and individuals contributions could draw more traffic.
A side benefit would be content being created for CE-Pro online that could even be touted on the main page, much like you are doing now for the forums in general.
For your consideration.
-Morgan