If I were you I would edit your grub.conf file and reinstall grub. It is really good that you created a boot disk
This is what you'll need to do...
1. Boot from your boot disk into RH9.
2. Open a terminal and as root, type vi /etc/grub.conf
3. Check out what you have in the file. Do you have 1 or 2 different entries? You should have two, one for you Win98 /dev/hda1 most likely, and the second for your RH9 install /dev/hdb1 probably.
4. After you edit anything you need, type grub-install /dev/hda
Before you do this you'll need to know what your hard drives are set to, eg. Primary Master, Seconday Slave etc. Also how many partitions on each.
If your Win98 is set to Primary Master and it is installed to your first partition you should have an entry similar to....
/dev/hda1 pointing to your Win98 (DOS) boot.
Let me know how you go.