Hp Proliant Microserver Raid 1 . Bios Vs Whs 2011

Hello,

I have recently bought a HP Proliant Microserver 40NL and installed 2x 2Gb Segate discs.
I set the Bios to Raid 1 after installing WHS 2011.
Then I read Windows Home Server Step by Step (By Terry Walsh and Jim Clark) and changed the two discs to Dynamic.

But when I click on the "Disc x" area to select New Mirrored Volume the option is greyed out.

Is this greyed out because I have chosen a raid 1 system in the bios and I should only do it in WHS or should I just use the bios setting?

Any help would be appriciated.

I have made no other changes or put anything on the drives yet as I wanted to set up the raid 1 mirror first.

Thanks