Is this card supported

[Adam Myrow]

Did you edit /etc/rc.d/rc.modules at some point?  If so, you need to find
where you had it load the 3com module and comment it back out with a
number sign.  If that's not the case, remove /etc/rc.d/rc.netdevice which
is the file that netconfig creates.  As a last resort, you could build a
custom kernel with just the module for your new network card, but this
shouldn't be necessary although I generally do so because I like to
customize my system.  Good luck and let us all know how it goes.