Hi Dominic,
Not sure about the static part at the top. It has the same colour at some of the content (overlapping especially bad in Chrome/Firefox), and it all gets a bit messy. - maybe put a solid background to preserve the integrity of the tabs when scrolling.
The positioning of the tabs is different with Firefox and IE.
In Chrome, the round corners on the tabs are missing, and in Firefox they are there, just a lot sharper than they are in IE/on the main logo.
Otherwise, a very professional and attractive looking site!
Maybe consider separate pages though... I like the whizzy scrolling bit, but with separate pages you can use a solid BG for the static header & with the single page, one could get a little lost in scrolling.
Will
p.s.
I find myself wanting the talking fish to jump when I hover over it (not a sentence you read every day). Maybe that's just me
