Unfortunately, Windows fdisk can't do anything with Linux partitions. So, you can run through the RedHat installation, until you get to the part where you create partitions to install... Then, delete all the Linux partitions, write the partition table, and exit the installer. Be sure not to touch the FAT32 partition.
If Linux was controlling your dual-boot, you will need a Win 98 startup disk to restore the boot control to Windows. If you don't have one, borrow one, or go to << www.bootdisk.com
>>. Boot from the floppy, and run "fdisk /mbr". This will restore the Master Boot Record to what Windows likes.
You can also use fdisk to create a new, second FAT32 partition. This will create a "D:" drive in Windows. Reboot to Windows, and format the D:, and you are good to go.
Of course, there is the small chance, through operator-error or not, that you could lose everything on the system. Be sure to have backups of anything you CAN'T lose before playing with the partitions. Anytime you change the partitions, there is always the chance something will happen and mess it up.