Just a quick post to relay a recent experience that was great when switching distributions in Linux.
I had a box running opensuse 11.4. I had configured this with a 4g swap, 40g OS (/), and a 56g home partitions.
Normally when installing a fresh distro the defaults will want to format all partitions and put them all within the OS partitions so you typically have 2 partitions. Obviously I created three partitions, this was important as my customized applications, vpn configurations, mail, internet apps, browsers ... are put into hidden folders in the home folder.
I wanted to install Linux Mint Cinnamon on this same box, but did not want to loose my browser, mail, development tools, ftp connections ect. configurations.
I put in the 64bit Linux Mint Live disc and booted it from DVD. I did the 'Install From Live' option and went through the typical first steps of setting up a new install. The important step came when the 'format partitions' option came. It had found that there was already one swap and two ext4 (OS and Home) partitions but it (by default) had selected each of these to format. I overrode these and set my own Swap and told it just to Mount the /HOME partition. I made sure to confirm that it was only mounting and not re-formatting the /HOME in the confirmation screen that shows what your about to do. The rest of the install was normal.
Upon first reboot, it finished its auto configuration and then asked for a user to be setup. This is important - I used the same username and password that it had in the previous distro install.
It continued and booted into my new profile but used the configurations of any of the 'default distro applications' that previously where created using OpenSuse 11.4. I had to install filezilla, and thunderbird (I was careful to rename the hidden .filezilla and the .thunderbird folders to oldxxxx). Once these were installed I deleted the new .filezilla and .thunderbird folders and renamed my _oldxxx accourdingly; both programs worked perfectly with all ftp/ssh configurations in Filezilla and all mail accounts in thunderbird.
I had to do very little tweaking and my profile and all the time that I had spent to get applicaitons working and looking like I wanted was preserved, plus all my documents, music ... where ready to go.
It was an excellent experience. I hope this helps you plan your next Linux install