Here walks in a friend of mine, running PCLinuyOS 32 bit, with a question.
We all know that if Linux would get borked (very unlikely) or needs a update via a fresh install, it is easy to leave /home untouched (going out from a rather standard install with swap, /, and /home).
But his question was: Can I upgrade to 64 bit from 32 bit and leave /home untouched as well?
I got to tell you guys .... I don´t know! Never tried or even thought about that option.
For what it's worth, I don't usually have a separate /home partition, but when I installed the first 64bit test image, I just copied my /home/polack directory from my 32bit installation to the 64bit one, and had no problems. A few of the icons on the desktop didn't have applications installed yet, so appeared as white squares with an X in them. After installing the proper applications I right clicked the icons, selected properties, then closed the properties window, without doing anything else, and the proper icons appeared, and the applications launced when the icons were clicked.
My current 64 bit /home/polack directory is a direct descendant of that original copy. All my browser bookmarks are still intact, as are my pidgin buddy lists, etc. I very much doubt that mounting the 32bit /home partition on the 63bit installation would give much different results.