Hi,
Im presuming from your issues Windows is bootlooping (where it gets to the logo and then restarts itself)
I would suggest using the a Windows XP disk to run as far as the setup, then when prompted choose R for recovery. It will list a choice of operating systems installed, normally only one option. Then run chkdsk /p and leave it for a few hours, if it is still checking for recovery of additional data after this time, chances are its stuck and will need to rebooted. There is a 50/50 chance that it will work if this happens, and better odds if it completes successfully.
Failing that you may have to reinstall windows.
Urban Kaos, November 2007