A common problem that many users face with Windows Vista is that the operating system fails to identify the second hard disk drive, usually the SATA hard disk drive. Often, the second hard disk drive might be recognized in BIOS, but it won't appear in Windows Vista. To solve this issue, the user has to so to the start menu, choose the computer option and click on storage. The user should then choose disk management. Once this is done, the user should alter the disk number to online mode. After refreshing, the user will be able to see the second SATAhard disk drive.
I recently had a hard disk failure so I re-installed Vista on what was my secondary drive. I then purchased a Hitachi 500g SATA drive. Unfortunately Vista will not recognize the drive. It doesn't show up in Disk Management. At times it will show in BIOS but not always, and even then it doesn't show in Vista.
Windows 7 users: Start-->right click Computer-->Manage-->Storage-->Disk Management. My second hard drive (both 1TB Western Digitals) was listed as offline. Right click the disc number (mine was Disc 3) and select online. You should be good to go - it worked for me!