I thought I had announced this before, but according to google I had
not. So...
Allegro NFSd is an NFS server that runs on Windows. I have personally
been using it for more than 12 months in a production environment,
using many different *nix clients (including various versions of Linux
and Solaris).
You don't need to be an Franz customer to use it. There is a binary
release available.
For more info visit this URL:
http://opensource.franz.com/nfs/