I noticed that this page is getting a lot of hits from Google searches for "NDISulator".
The NDISulator is an invention of Bill Paul (wpaul at freebsd) that allows you to use Windows
network drivers under FreeBSD.  Here's a few steps that should get you going with it.

1. cvsup to the latest -CURRENT.  The NDISulator isn't available under 4.x.
2. Install the base NDIS code.  cd /sys/modules/ndis; make; make install
3. Locate a Win2K/XP driver for your card.  The driver should include a SYS and an INF file,
   usually in a directory called WIN2K or WINXP, but they could be hidden somewhere else.  For my
   Linksys card, it was bcmwl5.sys and lsbcmnds.inf.
4. cd /sys/modules/if_ndis
5. cp /wherever/.../sysfile.sys .; cp /wherever/.../inffile.inf .
6. ndiscvt -i inffile.inf -s sysfile.sys -o ndis_driver_data.h
7. make; make install

## im upto here...

8. kldload ndis; kldload if_ndis
9. ifconfig ndis0 (standard ifconfig arguments)
   For my Linksys, this was ifconfig ndis0 inet 192.168.0.3 ssid etcetc channel 11 wepmode on wepkey 0x12345(etc.)