I think the source of all the problems with my Team Foundation Server install stem from the fact that I was using Beta 3, not Beta 3 Refresh. I'm very red faced - but in my defence, I must say that the download option from TAP was not that obivous - it is now, but when I downloaded it the only clue was a folder called "vstf.b3.rtm".  Anyways, I'm downloading the correct version now so by this time tommorow it should be working. .. (famous last words?).

On the up side, I'm getting very good at installing SQL Server!