Speech is definitely 44.1 khz there, and music is MP3 (I don't remember what exact quality though). I was talking about sounds like Combine talk, zombies, headcrabs, etc - I was surprised to know that they're 22.05 khz.

>In terms of games generally, you have to think about the fact that while compressed files are smaller, having to decompress is more math on top of the game for the CPU to do.

Yeah, correct. That's why there aren't really any compressed files in any game - back then it was a bad idea because of CPU overhead, now it's a useless idea because it's not much of a disk space comparing to all the other resources.