Keep getting BSOD error, all I did was attempt to replace the motherboard

[Whitecrow501]

I recently bought a new motherboard and quickly realized it would not fit into the case I have. I had already disconnected and removed the original board, and as regretfully such I put it back inside, reconnected all the wires (both inside and out) and turn it back on. Keep in mind I STILL HAVE VISTA, and before the os would boot, I got Large blue screen. I have searched and searched the internet trying to figure out what I had done wrong. From what I could find the error has something to do with the hard drive, so ran a chkdsk and found no problems with the hard drive, and I checked the ram just to be sure. Everything is plugged in and clean of dust. I am completely lost when it comes to this thing, and I naively did not back up the computer beforehand, so re installing the OS is a no-go. So to all you computer guru's, please tell me what I can do to fix this thing?

 

[Tmagic650]

If you can get into the bios, check to see that the boot hard drive is in the proper area of the boot list. Also make sure that the drive setting is still either IDE or AHCI