Here are my two cents:
– I like the fixed width centered design. That is how I design all of my sites (well, most of them)
– I like the combination of green and gray too. Looks good.
– I would change the header graphic to something simpler and not as crowded. It deters attention from the main content of the site.
– The site looks a little spammy. I’m not trying to offend you or decrease your site’s value. It just looks that way for the amount of links you have toward the top of the content. Try to put some content in there (maybe a short article)
– You are not using your footer at all. Use that space, put some information, navigation links, etc.
– Add more content to the whole site. Your articles on top of every page are very short. Write better articles targeting the visitors not search engines.
Hope that helps.
Cheers and good luck