The site design is, as noted above, reasonably attractive and I think visually pretty clean – much better than a lot of sites. (However the backgrounds – header area and body – aren’t doing you any favors.)
I strongly agree with the suggestions to get rid of the tables and to start using HTML5.
But the first thing I’d address is correcting the substantial number of validation errors (mostly HTML, a few CSS).
Also, consider making the design flexible or better yet responsive – IMO the days of fixed-width designs have passed, and if this is to be a portfolio site touting your mastery of the latest best practices, RWD should be near the top of your list.