I like the overall layout (suits the game forum theme). For your header, I really like the layer style & font you've used. Maybe try making the blue slightly brighter so it stands out more? For your yahoo ads: Try making the link names the same brighter blue as your other links (suc as: "News and Announcements ") so it's more visible and people will be able to read it + click on it if they too are interested.
a friend of mine made one similar...somehow I never understood the obsession with halo, I did like the PC version...as for the site, its good man.
It looks excellent, keep promoting it, attracting users and stuff and by launch time you could have a real money maker.