Ethernet Cards/Chipsets

Most ethernet devices (actually, network devices in general) are supported, so don't worry too much about it.
Tulip clones are cheap and tend to work well.
Linus has an eepro100, so that's a fairly safe bet.
NE2000 clones and their cousins RTL-8129 and RTL-8139 work well and are cheap, but they don't perform that well under load.

Most ethernet devices (actually, network devices in general) are supported, so don't worry too much about it.