the way it sounds, you would need to edit your boot.ini file, then simply format c: (do this by right clicking MY COMPUTER< choosing MANAGE, then DISK MANAGEMENT when it pops up. Right click the c: drive and choose format (choose ntfs)
To edit the boot.ini file, I would need to see it before making a suggestion.
Right click MY COMPUTER, choose PROPERTIES< choose ADVANCED< click the startup and recovery button, and then the EDIT button. Will open up boot.ini in notepad. You can edit it and then save it, but the ARC information is a little archaic and counter intuitive to a lot of people (for example, the first device is 0, not 1, and the second device is 1, not two, except for the partition number, where the first device actually is 1 and not 2...see what I mean??