[fredjacksonsan]

It does sound like the battery, since that is the only thing that's changed. If a battery is more than 4 or 5 years old, discharging an automotive battery will often kill it(and sometimes on new batteries also).

While you're having it replaced, see if you can't get the alternator checked at the parts store to make sure that is working properly.

Lastly, insure that all the connections to battery, starter and ground are all tight.