If the alternator is good (recharging the battery as it is supposed to) and you've gotten a new battery (that doesn't have any bad cells), I'd start moving towards doing volt testing to see what else is drawing from the battery when the vehicle is off.
To double check, make sure to test the battery while the car is running which will tell you that the alternator is doing it's job too. Then test the battery while the car is not running. Should tell you that both are OK right away with the difference.
If those are fine, chances are that it's a wiring issue and something is still pulling voltage while the vehicle is off. Sounds dumb but have you made sure that your dome light isn't on all of the time? Once you clear that off the list, it unfortunately becomes a lot more difficult as you will need to start voltage testing everything.
I feel for you, not an easy thing to find! Might be worth taking to a shop that can hook it up to the computer...I think a 2004 would still have a pc module wouldn't it?
Good luck!
Flushy