Windows 7: error loading operating system

hello i need some help with this one, i guess i should explain this from the start, i installed windows 7 64bit ultimate (7600) a few weeks back, but just a few days ago i decided to install windows xp home sp3 on my back up drive for other reasons, qoute me instension was not to have a dual boot partitions, i unpluged the sata cable on first hard drive that has windows 7 installed, and just booted of my second drive with xp only, now today i dicdided to reformat the back up drive with xp cd, i shut the computer off plugged in sata 1 cable back to first hard drive, went into bios set sata 1 option to auto detect then rebooted pc thinking it would load into windows 7 but i get this (error loading operating system) with a black screen, so i thought maybe some how my hardrive got currepted so i attempt a few things, i reinstalled windows 7 without formating, reason why cause i dont want to go trough all the hassle to reinstall all windows and all my games apps etc, so after a reinstalled i thought everything was fine, i restarted computer i got the same error, rebooted 6 times with no luck, the only way i can load into windows is by putting the windows 7 disc back in

why is it people respond to other posts but not mine what gives

can i get some help hear please and ty, i am waiting on some feedback so i can restore my os back to orginal state, i don't feel like reformatting and reinstall all my games etc

have you tried reading some other posts? there are plenty here about people dual booting. try this one Setup a Dual Boot Window 7 (main), XP Pro secondary

if u read correctly, i am not looking to dual boot