When creating an Network Load Balancing Cluster in NLB no interfaces were coming up as being available when creating the cluster. This was on Server 2008 R2, however it would be the same on Server 2008 and possibly 2003.
Interfaces available for configuring a new cluster
I did have two interfaces available on my server however:
The server that I was trying to provision NLB for was virtual using vSphere. The reason no interfaces came up was because this server was cloned from a template using VMWare. To resolve the issue I used Sysprep located in c:\windows\system32\sysprep on Server 2008.
See the following link for instructions on how to do this:
I recommend syspreping all your server templates regardless which hyper visor your running.