With Ubuntu, if I haven't updated for a couple of releases, can I just 
skip to the current one, or do I have to go through all of the steps?  I 
guess I have 10.10 on one machine, so to get to 12.04, do I have to go 
through 11.04 and 11.10 to get there?

At what point is it better to just install the OS from scratch?

Mike