Thanks guys, some interesting suggestions.
Spent way to much time today looking at enterprise level storage to run our VMware ESX servers off of - trying to narrow the field a bit before we start bring in sales guys. This decision may drive our cheap storage decision - ie keep the interface the same, and interoperability.

Back up wise we're not that concerned, most of our data gets old very quickly & can also be reproduced easily. Having said that there are certain bits of data that we can't lose and we currently have a less then ideal backup store for IMO. But that is next years worry.