HD partition options/suggestions for new virtual server setup

I am in the planning stages of a new server. The initial hardware will include a Compaq DL380 with 2 72GB 15K RAID 1 connected to a 12 bay external SAS enclosure. On this enclosure I will be running 8 146gb 15K drives split into 4 RAID 1 arrays. The DL380 will act as the host OS with MS virtual server. Each external array will independently contain one of the following. 1) W3K server (web hosting), 2)W3K server (email hosting), 3)W3K server (SQL Server), 4)Red Hat (LAMP). My question revolves around partitioning the arrays. Should I split each array into 2 partitions one for the OS the other for data? I understand this offers little performance benefits but would management/recoverability be easier/better? Any thoughts appreciated.