Much Improved!
A couple of comments if I may:
I agree, the background is a bit too bright but i don't think it takes anything away from the design.
Your centre I-frame loses it's bottom edge until you scroll down. The solution: Place the i-frame inside a DIV so the borders appear constant... for the content that appears inside the i-frame, do not have outer borders.
Biggest improvement is the header! It is simple and looks good!
I don't mind the nav buttons being seperated, but typically sites do not space them out. (ie: no space between buttons - just stack them). You may not want to do that unless you have more pages to link too... or you could stack them and use the extra space for something else.
I still find the nav buttons a wee bit hard to read with grey text on a grey background - but it's not too to bad.
The left column is longer than the right column in firefox but not in IE... causing the site to appear unbalanced. BUT THANK YOU THANK YOU THANK YOU for losing the "Optimized for Internet Explorer" - blasphemy! In firefox, there is extra v-space above and below the image (of the lake). Look for a vspace tag in your <img> or possibly a padding-top & padding-bottom in your css.
Centering is a good idea, but with the Google AdSense on (controlled by your host I believe) on narrower screen widths it could cause it to appear over top of your content... so I see why you've left justified the site.
Well, that's my 2 cents.
Mike.