Good news.
Concerning the second SATA drive:
Probably an incorrect setting in BIOS that makes the computer look for Windows on the wrong HDD.
In the Main menu > Configure SATA as IDE.
In "Boot device priority" > the "old" SATA drive should (of course) be #2 - after CD/DVD.
RAID should be disabled.
What was the error message when you installed the second HDD?