Thanks for all the answers and ideas, it made me think of my drive configuration a bit more.
I'm thinking of 2 SSDs one for OSX and one for Windows, the four main drives for data. I'm mainly going to be running VMWare with a number of Windows Server 2008 virtuals.
The SSD for OS and applications.
The first HD partitioned for OSX and Windows data swap files etc, the other three drives to be used for the main drives of the VMs. I was not thinking of raiding these as I think I could better performance with a virtual on each drive rather than three virtuals running off a single striped drive.
The question is how do I connect all the drives so that the first SSD boots OSX, the second boots Windows and the rest are just available. I know I will need an extra PCI SATA card but which would be the best drive(s) to connect to it.
Comments appreciated - I know how I would do this for a PC as it would have a case with space for 10 drives and 8-10 SATA connectors, but I'm new to MACs.