I have a slightly different take on this.

My friend had the same problem...bad alt, replaced it, and the next day, she started it up. Right when she put it in drive and revved to go, those lights came on. We turned off everything in the car, except the engine, and drove it to pep boys where she had it done. Turned out the alt/PS belt was too tight, and snapped.

I don't mean to seem so simple and stupid about this, but are both belts there and turning while the car is running?

(P.S. - My SVX has the original alt in it with a 2yo 800 CCA battery (according to the reciept I got with the car...a Costco one, none the less lol). In the sub zero temps in the city, it starts and runs fine (knock wood...). But I can verify that the stock alt is weak for the car. While I was driving in the NYC blizard in mid december, with front and rear wipers on, 80 watt aftermarket low beams and 55 watt fog lights on, my stereo, and the defroster on medium heat, at a stoplight, my usual 550 RPM idle crept up to about 800, i'm guessing to run the alt harder to make more juice. No adverse driving effects or stalling or anything, but...Is that a normal occuracnce and has anyone else seen this happen? Does it mean my alt is on its way out, even though I was using all those accessories at the same time in 5 degree weather?)