Make sure to clean up the battery terminal posts really good. A battery terminal brush can usually be purchased for under $5. If you are going to get the battery swapped out, go to Wal-Mart or a Sams club (if you are a member). The more expensive batteries will offer better warranties. Finally, go to an AutoZone and have them test the charging system. They will do this for free. This will help you in the event that the alternator is on it's way out.
Hope all goes well for you.