Steam's not the devil that people like to think it is, unless you are on dial-up or an equally slow internet. From experience, it's absolutely horrible on dial-up.
Try dial-up on another floor than the gaming computer. I've got to tear it apart and haul it down 2 flights of stairs to connect via dial-up, wait 12-20 hours for it to do its MANDATORY updates at dial-up's lethargic pace, then drag it all back upstairs again. The fancy "Don't Update" option only works if you're not actively playing the game; it still does updates every time you load the game; otherwise Steam automatically loads updates even for games you haven't played in a while. Worse, from what numerous people claim, Steamworks will attempt to "reverify" the installation after about 2 weeks offline, so you've got to keep doing that over and over. Steam is NOT going on my system, sorry.
The only way I can get some of the bigger mods is to d/l and burn them to CD before or after work, and carry them to my PC via "Sneakernet".
Actually, I don't have a MW char active at this moment; I'm finishing up a long, drawn-out WWII historical strategy game campaign before I get back to it.