Partition Issues on RAID5 Setup

Hey Everyone,

ASUS M3N79-T Deluxe motherboard
(4) WD 1TB Caviar Black SATA drives

I am running Vista x64 Ultimate.

The issue is that I set up a 500GB primary partition for OS, games, Office, etc. I tried to set up the other 2.xTB of space into two 1TB drives but I was only given the option to format the volume into a 1.5TB and the rest is in a partition that I can’t format or alter in any way.