I disabled Enable Controller BIOS control, then disabled HW RAID from the BIOS setup screen, then booted with a live Ubuntu Desktop 11 CD only to clear RAID's metadata based on the information on that page. But when Ubuntu is loaded (GUI), I opened the terminal and issued the os probing command using sudo, it returned nothing ! And no drives could be seen so the dmraid command didn't find anything to work on !
And when I enter the boot screen to chose a device to boot from, I can't find the "Hard drive C:" label which has my USB in it's menu. But now it's gone ! I've been messing a lot with the BIOS config but I'm not sure which mistake did I make.
It's all about clearing all the RAID data from the disks for Ubuntu Server installation to see the disks and continue the installation using Ubuntu's RAID configurations.