Here is the release history for HP-UX. Moving away from 10.20 is a good idea since HP dropped support for it on June 30, 2003. But moving to 11.00 now? Note that HP will drop support for 11.00 on Dec 31, 2006. If you hurry, you will have a supported Operating System for 3 weeks or so.
Those K boxes are pretty old too. You don't say which model you have. You might want to look it up on
this page. If these boxes are doing anything useful, it might be time to replace them with a more modern PA-Risc 9000. You need to do that soon, the sun is setting on PA-Risc. HP has stated that they won't design another PA Risc CPU... they are moving to Itanium. If you wait too long, you may be faced one day with a broken and unrepairable K box and no supported PA Risc box to replace it.
I don't mean to rain on your parade or anything. But it is better to found out about your support situation now, rather than during a crisis.