Car battery dies while driving at night? on 2002 Saturn L100

Ok, my battery light has been on pretty constant the last month or so. When I had my oil changed the mechanics also said my battery tested low and should be replaced. I didn't heed warning and continued to drive the car. I figured the old alternator (We just had replaced 3 months ~ ago) drained my battery and I would change it when I had the money. My service engine soon light is on almost constantly (I've had it checked out and it reads something with the cadiledic coverter which I've had checked out multiple times) the battery light is on and thats it.
While driving home last week (at night) my ABS light came on the car became pretty hard to steer my headlights and inside console lights started flickering and the car wasn't accelerating (Like it didn't have any UMPH!). I decided...I can't really drive home with flickering headlights (a 42 mile drive home) so I stopped, shut the car off (thinking it might reset something), and attempted to restart the car. To my dismay the car wouldn't turn. My brother picked me up and took me to get a new battery (assuming that was the problem) I was able to drive it home and it worked fine for a couple of days.
Last Tuesday, driving it home from work again (also again at night - 1st time night driving since the break down and new battery) The car did the exact same thing. The ABS light came on and then a few seconds later flashing console lights and headlights. I was able to get a friend to give me a jump and drive it somewhere to park it for now (It made it 3-4 miles without a problem other than a battery light on). It is still sitting there and I'm trying to decide what to do with it.
New alternator, new battery...only thing left is an electrical problem? The car is only, MAYBE worth $2,000-$2,500 and I'm not sure how much work / money I should be or want to put into this thing. If anyone has any suggestions I'd be more than grateful!

Asked by for the 2002 Saturn L100
you need an alternator. low voltage is causing all the other issues but the check engine light. you need a cat converter with the 420 code.

This ans. was not thoroughly explained b/c he had a new battery and a new alternator. What are the other possibilities? Could there be something draining the alternator & battery?
1 more answer
Have you checked out the belt that goes around the alternator that was my problem too just two days ago. I didnt notice my belt was broken a church member did! I was about to buy a new alternator.