You can use the RH installer to remove the Linux partitions... Run through the installer to the part where you make partitions, and delete the Linux parti's off the drive. Then exit the installer.
How to restore the MBR depends on the version of Windows...
If you have XP on the system, before removing Linux, boot to XP and go through the Control Panel and find the hard-drive control section. I don't know exactly where it is. You'll be able to restore it in there.
If you have 2000, I think you'll need to boot the install CD and go through the recovery system.
If you have ME/98/95, you'll need a boot floppy. Boot from that, and run "fdisk /mbr".
You might want to be sure you have the MBR fixed before removing Linux.