I didnt get on the freaks and geeks wagon until earlier this year, but it was fucking GREAT. I couldnt make it through whatever the sequel series was though. Cant even remember the name.
You are probably talking about Undeclared and it wasn't a sequel. It was just Judd Apatow's next tv series, which also lasted one season. I actually enjoyed it quite a bit and enough to buy it on DVD but it was no Freaks and Geeks at all by any means.