What drive is arriving tommorow? you'll be limited in size by the smallest drive in the array. Plus it's not a great idea to mix and match makes/models/revisions of drive if you can help it.
That may explain why my old RAID setup didn't work too well. Getting a 320Gb WD Caviar Blue, probably be alot quicker on it's own than the 2 old HDs in RAID setup.
Waiting for Windows 7 to come out before I get another hard drive so I can get an OEM copy.