Using hardware load balancers is strongly recommended. Microsoft Windows® NLB may be used for evaluation, test, and pilot systems or for small, nonmission critical deployments.Furthermore there are the following limitations with using NLB -
So the short answer is - don't do it !
1. Remote administration using the Live Communications Server snap-in is not supported. The front-end Enterprise Servers will have to be managed by running the administrative snap-in locally and not from a remote computer.
2. Multiple pools within an organization are not supported.