I used to play AOE2 quite a bit (mainly DM, some random map). Played for about 5 years, got pretty good at it. I haven't played in quite some time though.
The best forums for AOC 2 currently are probobly Legion clan forums. I don't know if they will have a AOE3 section.
http://www.thelegionclan.com/about.php is the address.
I still don't know if I'm going to get it or not. AOE 2 was such a good game, and I don't think AOE 3 will live up to its expectations. There was a demo version that I saw linked to SuNo clan (a DM clan) at
www.sunogaming.net . Page is down for a bit though.
If you get it, write some thoughts or PM me about it. I might pick it up if its good.