To change MBR (Master Boot Record), you will have to rewrite it. To do this, you can use fdisk that comes on your Win98 CD. Just type
at the dos screen. Be aware that this might lead to problems, if you don't know what are you doing.
I did this more then once, and it helped me to avoid reinstalling of a good system.
But first of all, read more about it. Here are some links:
http://support.microsoft.com/kb/q69013/
http://www.computerhope.com/issues/ch000175.htm
http://www.fdisk.com/fdisk/
http://www.pcguide.com/ref/hdd/file/progFDISK-c.html
Good luck! :bye: