How do I change the boot drive in bootloader


I had a single drive system with Windows 7 loaded on C:\. It's an older IDE drive.
Recently I added a 2nd drive (SATA).
The system calls the newer drive disk 0; and the original drive disk 1.
I partitioned the newer drive into 3 partitions: swap (drive letter is S), data, and backups.
My problem is that somehow the bootloader has an entry Boot Drive S:\

What do I have to do so that my system will boot from C:\, and the bootloader will correctly point to C:\

Thanks for your help,
Thank you for the quick response. Pardon my computer "ignorance", but does anything have to be moved from my S_Partition to my C:\ drive to make sure it's bootable from there?
Remember to change the BIOS to boot from the old HDD too.
("change boot drive" will copy the boot files to the specified location, so unless you change the BIOS sequence, the originals will still be controlling the boot. They remain in place untouched.)