Hey J,
Here's my take on the solutions: call these mobo maker's tech support(and ask about T-Bird support of these mobos): Asus K7M, Fic SD-11, Freetech P7F200, Gigabyte GA-71XE, Microstar MS-6195, Shuttle Spacewalker AI61, or Soyo K7AIA, after you find out if they are in stock of your favorite retailer. I know the Shuttle AI61 will support the T-bird Slot A, because that is what my old computer is running(with a Bios update). I would not trust any vendor with these questions, try to talk to a mobo techie! If I were you, I would consider getting a new Socket A mobo and CPU, most Slot A mobos only support ATA 66, and 2x AGP. If you have to spend the money and time to put together a system why not just write off the Slot A cpu, and start fresh, even if you have to get a cheap Duron(you can always replace it when you have more $$$$, if you need the speed).
Hope this helps a little & Good Luck!
Peace Out...........tile
Keep Hope Alive!