I agree with the logitech recommendation. I have the mx700 duo that you can find
here for $66 shipped
I don't know what the lx700 is like, but I know I really like my mx700.
As for the soundcard, I think the options imverygifted mentioned are right on. For gaming, the Audigy2 is a really good card.
I have the AV710 and it's more suited to music I'd say. It's ideal for stereo listening or if you want to hook up to a receiver or something, but it doesn't have all the nice features the audigy cards have.