Hey Xanathos,
I have a few comments.
There appear to be two navigation bars although one can be classified as a subnavigation bar? The one on top and the one on the left side. If I were you I'd go with the left one only.
The event calednar should be in line with the 'latest news' subheading. It looks a bit out of place right there on the top.
The search text box on top of the page should be more prominent and it seems odd to be right on the top for that specific layout.
Are you planning on having ads on your website because apparently theres an Advertisement space above the 'Latest News' and 'Popular' subheadings. That space is taking away from your whole site.
Those green boxes are a little too much on the buttons don't you think? I dunno this is just my opinion. I'd keep it simple, just a color change on mouseover.
You should put in a FIRST logo on your header, its one of the requirements on the FIRST website marking scheme I believe.
I love your header, it's awesome!
All in all your site looks really great, nice, clean cut and sharp except for the above mentioned. I know you can make an awesome website since you're almost there.
Take a look at
http://www.dublinrobotics.com who also uses the Mambo tool. I think they have a pretty good layout too.
What I have said above is just my opinion and how I feel, others might think otherwise so don't just listen to me
