I can't access my floppy drive when running a Red Hat Enterprise Linux 5 xen kernel.

This is a known bug that has been around since Red Hat Enterprise Linux 5 GA. The problem is being tracked via private Bugzilla 401081 "Floppy disks do not work with Red Hat Enterprise Linux 5.1" and will be fixed in a future Red Hat Enterprise Linux 5 minor release (update).

The workaround is to install and boot a non-xen kernel in order to access the floppy drive to read/write/access a floppy diskette.