Reinstalled BG1 to try playing through again (new to the game, but got frustrated with the interface first time I tried a few months ago). But when I played this time, I noticed that there were no character voices, either at the narration intermissions, during gameplay, or even at the character creation tests.

The only advice I've found for similar problems on these boards has been to disable EAX, but the "environmental audio" checkbox in the sound options is totally disabled for me (unchecked, but I can't even check it either). Not sure what to do, and it's especially frustrating because everything had seemed to work just fine the first time I'd played this, on this same Win Vista machine. Already tried uninstalling and reinstalling to no avail. Halp?

Sigh. Turned out to be a hardware fault caused by user stupidity. Apparently I've gone 3 or 4 months without noticing that the center/subwoofer line of my speakers was plugged into the microphone jack on my soundcard.

Lesson learned: never underestimate the potential for user error to be at the bottom of any problem, even when the user is you.

Well, at least you've found the solution. The Dutch have a saying: being erroneous is being human (well, that's my best translation I can come up with right now).

Sounds like the old "To err is human" saying we have over here.

That's the proper translation of the dutch saying. Yours is more accurate and my translation was.... erronous :-)