Hi Zohaib R,
Thanks for your reply. I updated the BIOS & further change the boot sequence. Boot problem is solved :). Now I can access the old hard drive beside the new one. However, I cannot format the primary drive of the old hdd (few system files are there which I could not delete). How can I delete these files to format it? Which tool should I use to repartition & format the disk and make it a single logical drive?