Wow, I haven't been on these boards for a while! I am currently using an IPTables Firewall/Router on our Windows network and I need to add some load balancing. I have explored Windows NLB(Network Load Balancing) and it only gets me half way there. I need to spread 90 connections on a given port across 4 machines: 23, 23, 22, 22. Simple round robin would be fine as long as it would keep it balanced i.e. fill in the gaps. I would also like it to monitor the port on the 4 machines so it will not send connections to any machine that is not answering requests. Any ideas would be greatly appreciated.

Take a look at ultramonkey load balancing and high availability tools for linux
Works very nicely for my company. We're load balancing web requests on three different ports between two servers, but it would be trivial to add more.

Dave