Ok an update, managed to connect to the NAS using iscsi and no issues there. Ended up running the wizard from the cd again and wiping the drives and setting them up as two independant drives. This is the only time its ever asked me to assign a drive letter which i did and can now connect all the time to the NAS through windows. Need to pluck up the courage to try the Mac again! Only issue i have is when transferring from USB to the NAS its really slow somewhere between 5-10mbs and the same over the network so need to sort that out