Consider cloud? (Score 1)

Have you considered any of the 'cloud' offerings? Amazon EC2 / Microsoft Azure could be an option, this will be able to give you scalability as am sure that your 1000+ visitors a day is a guess. You can then bring up some of your services and grow with demand. Your 6 servers, clustered with a load balancer will quickly get expensive. Give it a go :-) SJJ