alt change
The gen2 alternators on atx's are pretty simple. 4 bolts (13mm) and I think the serp belt tensioner is 18mm. You will have to remove the idler pulley to remove the bottom bolt on the alternator. As mentioned it is pretty easy.
My starter was apparently draining my battery so bad that after several starts the alternator couldnt replace the charge in the batt quick enough (I do alot of starting and stopping) - at least thats what i believe. I replaced the abtt with an optima battery. It still went dead a couple of days later. Changed the alternator. Still went dead. Then changed the starter because a mechanic told me that although rare, starters can apparently draw far too much amperage during the cranking start cycle and literally drain batterys dead, so much so that an alternator cannot usually re-charge the battery. I thought this was a stretch, but so far it has proven to have solved my battery drain problem.
Sounds as though in your case it's just your alternator. Most places, when I called around for prices, offer the lifetime warranty -well 'limited' lifetime - meaning if it fails for reasons related to the alternator itself it's covered, but external damage no.
Good luck.