If you want to repartition and format the hard drive, boot the system with a Windows 2000 boot disk and type fdisk which will bring you to the screen you will need to define the partitions for your system. Then format and reinstall your O/S of choice. This will get rid of the dual boot issue, provided you wipe out all partitions with fdisk. If it's still a problem, try fdisk /mbr which rewrites the master boot record of the drive.