>> Just wondering this but why do you have to load PC games onto your hard drive as apposed to console games? I've always wondered this.
Because CD drives, as fast as they are, aren't fast enough to run games, and still do the real-time decompressing of content that the EXE invariably does while the game is running. And correct me if I'm wrong, but I think the Xbox has a hard drive...plus console games have a lot less content than PC games (partially due to their fixed hardware that has limited ability), which routinely ship on more than 1 CD now...
DoD Source is the Source-engine port of Day of Defeat, which you can find more about at dayofdefeatmod.com. And you don't have to pay extra for it either, you can get it free right at that site. Not the Source-engine version of course though.
Counter-Strike is also free at counter-strike.net (again, not the Source version), along with a variety of other great mods, like Natural Selection, Firearms, Science & Industry, etc. Of course though, all these mods are for HL1, so if you don't have HL1, you won't be able to play them. You'd have to wait for HL2 mods. Hah! Ha hah! You've should've bought the first one!