Normally the setup would choose an 'nv' driver for your xorg.conf file found in /etc/X11 directory. You can peek there, near the bottom and see if it did. If it did put it in and things are not displaying then you could change the nv to vesa as that will work with nearly anything.
The formal way would be to fetch your ports and system sources (see chapter 5 of the Quick Guide) but FreeBSD just this week changed from using xorg 6.9 to 7.2, a _major_ mod and from what I've read on the FreeBSD lists, compiling the drivers for older nVidia cards is borked right now. They will get it right in the near future but your best course of action at the moment is probably to do nothing.