Thanks for the continued replies . . .

I don't get driver updates from Microsoft. Microsoft OS Updater wasn't the problem. I used Driver Detective and installed a secondary Vista driver not meant for my XP system (got lazy, didn't look too closely . . . hadn't had any trouble from them before).

I spend so much time in front of this box 'for work', tinkering isn't fun any more.

Ended up getting a chip-set driver from Intel, after I let them run a scan.

Speakers are working now.