Think the design itself is quite good. Like you said, "bit rough around the edges" for example clicking a new tab should not center the tab on the screen. Your using vertical-align: top; but it still is centered. Maybe its just Firefox 3??
I've just created a similar site, cofounding.slinkset.com, the idea is similar, except its focus is on people who have already started creating or are nearly complete with their startup and want to share, get feedback, or join up with other people in a joint venture.
It's private so please send me an email (on my yhacker profile).