If You have Promise on-board RAID controller, You can safely disconnect both drives. You can then put them in the motherboard's ATA connectors (the ones You have your CD drives connected). It will boot from either of the drives. DO NOT delete the array from the BIOS, as it will overwrite the MBR on the drives. Just unplug the drives. The array will delete itself from the BIOS.
NOTE that this applies only to Promise controllers. I have of no experience of Highpoint or other manufacturer controllers.
A64 3000+ (1GHz@0,85V), 7000AlCu@5V, MSI K8N Neo, 2x512MB Kingston VR, HIS 9800PRO IceQ, 2xSP1614N (Nidec), ZM400B, Nexus 120mm@12V, NEC ND-2510, 3700BQE, Nokia 445PRO