Yes, basically it looks like you have four possible options:
(1) The best one - if you have made a system restore point before things went wrong, you might be able to access that. Do a google search for that. But, this will only work if enough of Windows is still operational.
But try it first. The worst you can do is to be no worse off.
(2) Second best, if you have ever made a registry backup, you could try restoring that. Not many people do that, though.
(3) You can try to repair windows.
If you have a system restore disk, you can select the "Repair" option at the first menu when you boot from the Windows CD.
If you never made a restore disk, select the "Install Windows" option and then a few clicks away you will be told that the CD has found a Windows installation. Tell it to repair that one.
(4) You can reinstall Windows from scratch and loose all of your settings. But your data should be saved (unless it sits in the "my documents" folder, which will be wiped clean.
You'll also have to reinstall most of your programs.