I'm currently using Ubuntu 14.10, together with Windows 8 as a dual-boot. I installed Ubuntu first, then Windows, so Ubuntu is my "main OS".
When on 23 April 15.04 will be released, will my current system automatically be upgraded to the new version?
Is it possible to remove my current Ubuntu and install a new one, without affecting Windows? I like to reinstall my OS once in a while to get a clean one.
No. You need to initiate it. It will be shown in the update software that there is a new release and offer you to install it. It will not be automatic.
Yes. I always do that myself: every new release I re-install over the old release. And I also always pick the "something else" option, format / and /home and add in my data partition without format (that one holds all my files). I like my OS to be clean and all software I installed over the past 6 months, sometimes never used or used once will be deleted.
Basically: burn the new OS to a DVD or USB stick, boot from it, install and pick "something else" or "replace 14.10" in the installation options. Just make sure to make a backup of anything important. There is a chance you mess up setting it up, having a backup of your files it your best bet in getting your data back quick and efficiently.
