I have a general question that I hope someone would be able to point me in the right direction.

I have installed ESX server 3 and successfully created a VM Server on a desktop PC running 2SATA disks.
The ESX server is installed on SATA0 and the Virtual Disks (VMFS) are running on SATA1
Note: This is for testing purposes only.

My question is, what is the best configuration for setting up the Disks/LUN when i comes to DATA, for example a file server.
I have created two LUN's(DataStores), one for the OS and an other for the DATA.
In doing so I have noticed that when I copy 500Mb from D: to C: (Of which are on separate datastores) it takes 3 times longer to copy. For example on a standard desktop it takes 30sec but on the VM it takes 1min 30sec.

Mind you ESX is running on a desktop PC. But I just wanted to confirm the best practices for configuring disks/LUN's when it comes to utilising data drives.

So if someone could point me to a document or forum it would be greatly appreciated.

Regards

Stephen.