Seeing as you didn't format the drive, your files may all be intact
If you have another computer
Sure, why not try putting the harddrive in the other computer
I assume the other is possibly using IDE cable, put in on the same chain
Ensure to set the drive as Slave, you will do this by moving the jumper on the harddrive to the proper location
If that works for you, back up whatever files/folders possible
Then put the harddrive back in the computer it belongs to
Replacing the jumper to the appropriate location
This time, do a Clean install
If it doesn't work for you
Take a look at the following link
http://support.microsoft.com/kb/314477