I am using Kubuntu now, and have a partition as /home separate from /. I want to install Xubuntu instead of Kubuntu. Can I do that without affecting my files at /home and is there any disadvantages of doing so?
I disagree, you should be able to install xubuntu without formatting the /home partition. Very few, if any .files will conflict between kde and xfce.
It has been the default behavior of the Ubuntu installer (ubiquity) to preserve /home, with or without a separate partition, for quite some time, .
https://wiki.ubuntu.com/UbiquityPreserveHome
Ubuntu now supports installations that preserve the /home directory when it already exists. To do this, manual partitioning must be used, and the partition on which data is to be preserved must not be marked for formatting.
https://wiki.ubuntu.com/komputes/HowToUbuquityPreserveHome
https://help.ubuntu.com/community/UbuntuReinstallation
Few people know it, but since Hardy it's possible to reinstall Ubuntu without losing the content of the /home folder (which contains program settings, internet bookmarks, emails... and all the documents, music, videos that you have put in it). Even if /home is not on a separate partition (which is the case by default if you did not manually separate it). Remark: this tutorial can also be used to upgrade Ubuntu (eg 11.04 -> 12.04 from a 12.04 live-CD).
The general concept of backing up your data before you install an OS applies, but, you should have a backup already.
