In short: don't use NFS on windoze...
I always get bad bahaviour with NFS on Windoze (speaking of win2k3r2 with sfu). After some minutes I get a complete loss of bandwidth and the performance is very poor (about 1/10th of a Linux NFS-Server on the same hardware). My tip: if it's possible setup a Linux server or VM for NFS. It's as easy as installing a linux distro and doing a: "mkdir /nfs && echo '/nfs *(rw,no_root_squash,async,no_subtree_check)' >> /etc/exports && exportfs -r" (as user root without the " 
--
There are 10 types of people. Those who understand binary and the rest. And those who understand gray-code.