Without wishing to appear bitter and twisted, a final word or two on the subject:
This upgrade was originally planned to take place in late December 2006. Problem 1; we couldn't get the upgrade kit in time, apparently a 6 week lead time wasn't enough for Cisco to come up with the kit.
Problem 2; as described above, kit apparently incomplete. Granted one solution might be to open a TAC case and get the missing bit posted for download BUT let's have a think about the job we're doing. This is a critical system, downtime is VERY limited. I had a 3 hour drive to site plus specially arranged downtime so I don't have much time or the option of hauling off and coming back the next day so you can imagine my delight at finding the kit was incomplete. Further, the time neeeded to raise the TAC case and go through all the hoops simply wasn't there. Luckily I had documented the original config (as well as backing it up and imaging the box) beforehand so was able to follow the path I finally chose. Had this not been possible I would have been left twisting in the wind ..... by Cisco.
My final advice to those carrying out this task, allow plenty of time to source the kit in the first place. Once you have the kit, read the upgrade instructions and verify you have ALL the software needed (note to Cisco; seems I'm not the only one to have received an incomplete kit). In addition, take careful note of the other tips very kindly listed above by others, many thanks guys for your input.
