So, I just had my battery replaced in my 2000 Pontiac Grand Prix with the 3800 in it and my SES light came on. How long should it take for the computer to reset? Or is there a way i can find the code to see if there really is something wrong with my car? I made sure the gas cap was nice and tight.

It won't just shut off. It needs to be turned off. Also, if it came on when you replaced your battery, I'd check all connections to the battery/alternator (especially for corrosion). Then, after cleaning it up (if necessary), take it to the local auto store for an OBD II Scanner and check the code.

My local Autozone is pretty cool. They have an OBD2 that they will help you out with, free of charge in some cases.

Same here, but you have to give 'em your license just in case you walk away with their tool..

The computer reset itself and the light went off. I read that in the owners manual.