Today's Steam update addressed my biggest gripe: if something gets corrupted then I have to download Half-Life 2 all over again. According to the site:
Steam Client Update Released
November 8, 2004, 1:39 pm · valve
A platform update is available and will be applied automatically when Steam is restarted. The changes include:
Added backup game files feature (right click on game)
Added purchase support for American Express, Discover and JCB credit cards.
Yep I can now back up my Steam games, including Half-Life 2. I dreaded something happening and having to wait another day or two to play.