ABS light & loss of Power HELP!!!

Hello, I just recently pulled into a gas station and when I got into my car the ABS light had come on and I was experiencing much dimmer interior and exterior lights, very slow power window movement, very weak a/c power, & and the automatic transmission seemed to shift much "harder". If you have any suggestions please let me know. I'm thinking it could be the battery, I don't feel that it is the alternator since I drove it for about 1&1/2 hours after the problem began and the car has yet to "die" on me. However don't get me wrong it feels like power is going to give out any minute. Please help.

Please note the make and model of car is 1998 Chevy Malibu, thanks