Many years ago I messed with an ISA 100 Mbps card in one of our - even then ancient - Netware 4 servers. I got it to work more or less but the performance wasn't exciting.
As Chris wrote, there's not much point in having a 100 Mbps connect reported that is no faster than a 10 Mbps connect.
I'm currently fiddling around with my new Prometheus bus board (anyone's got a spare Voodoo 3?) and a RTL8139, but I have no hope that throughput moves beyond 1 MB/s, if at all.