About that monthly subcribtion. You can use steam all you want with a valid cd-key. When you subscribe for somthing around $9.99 a month you can get all the games that come out for it. I'll start naming them off I guess, Half-Life,Half-Life2,TeamFortress2,Counter-Stike:CZ, and what ever they think of realeasing. If you play on a valid Cd-Key then you only get Half-Life and its mods. Hope that clears up some things.
P.S. This is what the FAQ said- "Is Steam really free?
Yes, Steam is really free.
Steam also provides access to several free products and services, like the dedicated game server, instant messaging, the game server browser, etc.
And if you've already bought Half-Life or one of the other Half-Life family of games, several add-ons are available via Steam for no extra cost.
After installing Steam, check your "Games" list to see what's available."