It's clear from the last day of searching that to find a AM2 processor with no more than 45W is nearly impossible. It's so obsolete it's like finding a new computer with Windows 3.1 on it. So....
Would it be possible to just put in a new motherboard into the existing case? All my HDs are SATA and could plug right in. I've been searching for that WinFast MCP61SM2MA-RS2H motherboard, but those aren't made anymore either. That computer was built in 2007, so by tech standards it's a dinosaur. I have no idea about replacing mobos.
I've got 2 new 4GB RAM sticks, and 2 good HDs that I would prefer to move over.
Thanks to everyone who's helped so far.