So I sent it back. They tested the board and said everything's fine.
Got them to send it back to me and still no luck.
So tonight, I took everything to a friend's place (computer guy) and he tried everyting he could think of to get Echo Mona on board.
Finally, he tried it on his own computer. NOTHING!
Turns out that PCIs are getting too fast for some of the old cards.
He said he'll try to find a way to slow things down a bit.
In the meantime, I'm back on the old Compaq C and Brenda gets herself a whole new computer.
Mona is discontinued now so I doubt that Echo have come up with a fix.
Thanks for the advice, all.