How do I tell if this is a usable motherboard?

Sure, it's still usable. If you have 5+ year old CPU's lying around.

The supported CPU list only mentions Pentium 4. I'm not sure how you'll go upgrading the BIOS to support newer chips.

So yeah, as mentioned above, it's not worth much at all. But at the same time, yes it's still usable for some things.
 
Back