I also suggest keeping the new design only as a natural evolution of the current one instead of a complete revision. I would also keep the green color scheme as I think that's by now probably a part of your visual identity which is good to keep consistent for marketing purposes. The Linode logo, after all, is green.
And I agree with others about
no flash and keeping things simple and breathable.
Also, I don't think "Web 2.0" design is
all about AJAX and it is not about complex designs at all. You can make a perfectly Web 2.0 style web site without AJAX. It is a much more broad phenomenon. Some elements recognizable in Web 2.0 are clean, lean, sharp spacey, uncluttered, easily readable designs. You probably saw that trend on the web already and by accident or not, Linode.com already employs some of these. It's by far not outdated as far as modern web design trends go.
Here are a few links I dug out of my bookmarks and web that might be helpful.
A List Apart is a well known web design instructional site.
53 CSS-Techniques You Couldn’t Live Without - maybe one of them catches your eye.
And for inspiration here are some sites where you can look at other well designed and cool looking modern sites. I love browsing these for inspiration:
WebCreme.com
CSS Elite
CSS Leak
And
more.
Also, if you'd like to launch a contest (buy whole or part of the design from the winner), here's a nice site for that:
99designs.com.
Cheers