there r two thing u must have to do
1) u must have to delete the linux partition, take the redhat 9 cd boot with cd and when it show grub screen to create the partition press ctrl alt f2 and run fdisk and delete the parttion or take the old version cd like redhat 8,7 and boot with that cd and delete the partition with fdisk and save the changes, after that remove the grub mbr entry by typing fdsik /mbr, after that run fdisk and create or delete the partition u try this it will work
thanks,
prashant