Citrix Xenserver is known to be based on Centos 5.x which is binary compatible to RHEL 5.
Dell offers a binary utility to upgrade your servers firmware and BIOS for Redhat Enterprise Linux.
Per default you will not be able those packages because Xenserver does not include one essential package: procmail
Also the base repo is disabled by default. To install procmail type:
Now you will be able to use the Dell firmware update packages on Xenserver.
This procedure was originally proposed in: http://forums.citrix.com/thread.jspa?threadID=235022