I have around 10 PCs, they currently have Ubuntu 11.04 running. I need to upgrade the PCs from 11.04 to 12.04 without downloading all the Ubuntu Packages every time. What would be the best way to upgrade them? I do not want to loose settings and/or data on these PCs, so re-installing is not an option.
Simple: Create a 12.04 CD or USB- Stick, boot it up and choose the upgrade option when asked.
You will not loose any settings and/or data this way.
EDIT: It seems I didn't do my homework properly, I'm sorry. You will have to do the whole procedure twice, first by upgrading to 11.10, and then to 12.04. I wish there was a better solution (besides a fresh install), however I don't know of any.