Hi!
I`m a new Linux user, but a couple of days ago I had a similar problem. Though I did a big mistake: I installed both operation systems (Windowsa and Linux ) to one harddrive, then deleted one of them!

I got the message that : Error loading operation system. Lesson: Never set up two different operation systems on one harddrive!
Whatever I did after that, I couldn`t make my windows run again inspite of several formatting and partitioning.
Finally, I got a software on a floppy: PowerMax . It is OK only for Maxtor harddrives. If you have Maxtor HD, download it free from the Maxtor homepage. If you run the "low level formatting" option, it may take a couple of hours to make your drive "like new". Of course, you will lose all your data on the HD. But, you will be able to mess it up again the way you like!
Vico