Just noticed that the NIC is not coming up as 100Mb/Full Duplex on our switch. It is coming up as 100Mb/Half Duplex. Both card and switch port are set to 100Mb/s. When I moved it to a different port as a test and forgot to change the setting on the switch, when the port came up it showed 100MB/Half Duplex. Messed around a little with the card settings, changed switches, same problem. Swapped cards with the same model card and same problem. So, I think I have identified the culprit.
Card is an Intel Gigabit CT, which shows to be compatible with FreeBSD. Intel has some info on their site regarding the card and FreeBSD. If I find a solution with this card I will post the info here.