It's not easy to get this thing going that's for sure.  One thing you do
need is an internet connect and firewall (if any) permission for the Steam
program.  I have been playing the stand alone version for a while, and tried
to run it the other day with the internet down - No go. It needs an internet
connection even to run the game just on your PC.  Can't say I've ever heard
of this for a computer game before now.  If you skipped the option to
register the game during the installation, (like I did ) you will need to do
this later from the Steam games list.

Okay just to update on this issue, I finally gave in and called Vivendi
Tech Support.  After checking all the installation paths and ensuring
that I actually had a steam account (even though I had been telling
them from the beginning what the problem was) they came to their
suggestion.  Delete the clientregistry.blob file in the steam
directory.  This and unchecking load startup items in msconfig allowed
it to do the necessary updates and decryption.