Do both HD's register in BIOS setup? Enter BIOS setup by tapping the key given for it on first boot screen as computer boots. What is the SATA controller setting?
Were your two HD's configured in a RAID array? Look at your setup literature or read your Manual to know for sure. Your Manual is on the Support Downloads webpage for your computer model.
Test your HD's one at a time with each plugged in individually, using GWScan full test and chkdsk /r from Win7 DVD/Repair CD Command Line.
Then wipe one HD to try install with it plugged in alone: SSD / HDD : Optimize for Windows Reinstallation