Actually, there may be another option, depending on how the manufacturer configured it.
I have seen many Windows 2000/XP PCs that had a full c: /i386/ folder that allowed a complete reinstall of the OS. Simply go into that folder and run winnt32.exe from inside Windows, or run winnt.exe if you are booted to a command prompt.
You may also be able to copy that folder to a CD, boot to a DOS disk with CD support, and then run the install, allowing you to format the drive in the process.
The i386 folder is a good thing to try. What happens is that whoever builds the PC copies that folder to the hard-drive, and then changes the setup path in the registry to that directory. Or at least that's the way it should be done.
This prevents the good ol' "Please Instert Windows Disk" message when adding new components like a new language. Sometimes that directory also gets created during the service pack setups, and does not actually contain the Windows setup files.