In this you can configure Steam to not automatically update said game, prevent pop ups from anything (friends coming online, friend message, game messages, achievements, etc) and various other emotional dilemma's you can take care of. You can even disable in-game community (pressing shift+tab). Also get to play with a neat option called "Run Steam in Offline Mode". The only time it requires you to go online after that is when your installing a new game that needs to register with Steam.
Steam is probably one of the best and well maintained digital distribution clients I've ever seen. The only grip I have would be like someone else posted is that when you install a game you don't exactly get to choose where it goes other then 'common' wherever you put your Steam folder at. There is a workaround but sort of a pain in the ass.
