crdy, there are training crits every tuesday evening in the south suburbs (south chicago wheelmen host) and that would an excellent opportunity to try racing in a low pressure learning environment.
But I agree with all the above posts...group rides, and for exactly the same reasons Homebrew lists. Check the Great Lakes forum. There are a bunch of north/west suburban teams that host fast rides. That will give you an opportunity to chat with people too...
I'm going to miss downers grove yet again this year. bummer....