i would have to say probably one of those $50 intel ones, like the 905b-tx or something like dat
but w/ personal experience, i *have* a "SMC EZ Card 10/100 Mbps Fast Ethernet PCI Network Card" model "SMC1211TX/WL" that ran at 44mhz PCI bus for a WEEK (this is a CHEEP nic, street value $15, found it for $8-$9 at some places)