Surround sound: what are the requirements? What uses it?

[Infohawk]

I'm in the market for a new computer. I do a lot of media viewing on my computer and I think it would be also cool to have surround sound for games.

Do a lot of games support surround sound?

Do you need a specific type of soundcard or do builtin ones work well?

What video formats support surround sound? Divx?