Cross-grading a Ubuntu install

Linux is wonderful at booting on any hardware. This has allowed me to move my original Ubuntu 6.06 server install to newer hardware several times, and upgrading means I have now Kubuntu 11.10 instead without the need to ever re-install from scratch (anybody can have their own opinions about whether this is a good or bad thing.)

Now the next step is to cross-grade it so I can take advantage of the hardware it runs on, and I wish this could be made easy or at least well documented. I have come across this [1] but did not try it yet.

[1] http://askubuntu.com/questions/81824/how-can-i-switch-a-3...