SATA Hard Disk Drive not detected

Hello,
I am using a Seagate 80 GB IDE hard disk drive for almost 2 years now, then earlier this week I have decided to buy a new hard disk drive which is Samsung 250 GB sata.
My operating system which is Windows 7 is installed in the IDE hard disk drive because I plan on using it thus making the 250 GB sata hard disk drive a slave,but my computer can't detect the new SATA hard disk drives though in bios it is detected only when your in desktop and go to "My Computer" you won't see the new Hard disk.
