I would suggest that the bottom of the search button be in-line with the box. By that I mean the shadow at the bottom.
Since the search looks like a tab why not make the other header links tabs? It will fit in better
Overall it looks nice so far. Who knew how good the default theme could look??
Are you going into implement any type of framework into your theme? either responsive or fluid?
I would put the search bar on top of the long blue bar now
I've moved this to the theme development section