3com is shit. period. all 3com hardware is shit. i don't care what you say, you just can't speak. it is shit.
realtek is shit. this is not a surprise, however, since their cards are 20 bucks at the corner store.
Why point this out? I got a 16 port 10/100 full NWAY negotiating rackmount switch for VectorStar's backside network. only ONE card negotiates: the DEC Tulip 10/100 card in vector. all the other ones (3com 590's, 905B and RTL8139) get half duplex. Of course, i can plug my dad's iBook laptop in and before the fucking monitor turns on it has a 10/100 full duplex link.
Moral of the story. buy DEC Tulip network cards exclusively. period. (Intel's would probably work very well too, but that's only cause they bought out DEC's networking divison when they realized how badly DEC owned them.)