NFS is in fact included in Windows 7, it's just not installed by default.
Copy/paste from answers.microsoft.com:
In order to activate the Client for NFS, go into the Control Panel, and go to "Programs and Features". In the left hand column, you'll see a link for "Turn Windows features on or off".
Select that, and it will open a list box that shows all of the optional components built in to Windows 7. Some are already activated. Expand the entry for "Services for NFS". There are two check boxes under that. Check them and hit OK. Windows will install those components and ask to reboot your system. Once you have rebooted, Client for NFS will be installed.
To use it, go to Administrative Tools->Services for NFS to configure it. Alternatively, you can use the command line program 'nfsadmin' to configure.
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