When you formatted your C: drive, you destroyed the boot sector.
Check into utilities fixmbr and fixboot.
Try ResQ from http://www.yqcomputer.com/
Or, you might try (as you say you can boot to DOS):
...to restore the Windows MBR, boot to DOS using your
rescue floppies, and run "fdisk /MBR".
If these suggestions don't work for you, try searching:
for additional alternatives.