Hmm...old cards (ISA?), no model #, no documentation, no drivers. That doesn't sound like a good place to start.
3COM cards are well supported under Linux, but they're much more expensive than other, equally well-supported cards.
Inexpensive NICs based on the Realtek 8129/8139 chipset (such as the SMC 1211) or cards that use the "tulip" module are a good bet.