depending on the driver, you may be able to get around this.
most installers (i.e. ones that aren't needlessly complicated) will
unpack a load of .inf etc files that the device needs to work, and then
automate the process of allowing windows to pick them up for use.
what you can often do (and good installers often have a specific
command line switch for doing this for exactly this purpose) is
install, examine the .inf files etc it generates, and then copy those
files onto the win2003 box. in device manager, use "install driver
from specified location" and point it at them. we have to do a lot of
buggering around with things like this when we're working on client
autobuilds - where you don't want the automatic build to be wasting
time prompting you do hit "next" etc.

whether all this mither is worth it, compared to getting another NIC is
another matter though!
ric