Consider this, most of the people at your new job probably know LESS than you do about SQL Server 2005. In my experience, the best way to learn about something is just getting down in the trenches and working with it. You can read entire volumes of information, but until you really have to solve a problem and go out and find an answer to it, how much of that knowledge to you retain?

Just go in with confidence and don't let anyone see you sweat. No one knows everything about everything, that is why there are references. There is no shame in not knowing an answer as long as you have the wherewithal to go out and FIND the answer.