Just as a bit of info; we just migrated from 7 dedicated servers to a rack system with 7 dedicated servers. Each server is a Dual Xeon running Windows 2003 Server.
We wanted a load balanced solution, but could not afford to buy the hardware version. So I did some research, and was determined to use Windows Network Load Balancer.
To architect our web farm; I decided to dedicate one server as our NLB cluster manager; as well as a db server. The other 6 servers will be host servers, running IIS, and Plesk. We are only using web traffic (SSL and non-SSL) and our email is running through another server entirely. Each server has two NIC's, one PNET and one WAN.
Through PLESK I setup the domain names on each host web server identically; as if it was hosted directly on that server. Then I had to manually go into IIS Admin to add the NLB cluster IP, pointing to the domain name of the site. Each host had its own live domain name (sub-domain actually). So I could go to each server directly, or to the cluster - depending on my needs.
To synchronize files across all the host servers, I used a software package called ViceVersa Pro 2.0 which is an awesome synchronization package for only $60. (http://www.tgrmn.com/)
Bottom line, its working wonderfully! I could not be happier.