If i recall correctly, before the 10/100 there was a strictly 10Mbit card, ( I have a 3com 10 Mbit PCMCIA NIC for a laptop that is strictly 10bit)but these days most cards are 10/100 meaning, depending on how the PC's are connected, (usually this is autodetected by your system) you will either connect at a maximum of 10Mbit or 100Mbit. I get 10Mbit on my wireless connection and 100 Mbit on my LAN (wire-based) connection.

BB