The portal page is OK, although I'm not a big fan of chartreuse (e.g. in the navbar). Perhaps you should go with the green you use for the "E" in your logo? The welcome header encouraging people to join is a nice touch.
The forum categories are well thought out, although for a site that's just starting out, it be a bit too many. Of course the forum style itself needs to be customized, preferably to match the color scheme of your portal page... but you already knew that.
- Dan