Run through the basics first: The choppy video and bad/no sound may not be related. So you have updated the drivers, that's the first step. Next, what videos are you playing? The ones in MOH:AA? I haven't played that game for more than 5 minutes, and it was only in a multiplayer environment, so I wouldn't know whether the cut scenes are stored on the CD or not. If they are, maybe it's your CD drive that's the culprit. The rest of your system is more than enough to play it with high graphical settings, so it's not that.
And what speakers are you using? All the nForce2's have the S/PDIF, so is that what output your using? Check the sound settings in both Medal Of Honour and in Windows, make sure they are at least using default, generic settings before you start pointing fingers.
Narrow it down, and report back, sir.

(geddit, Medal Of Honour, military? LOL...)