Here's a walkthrough of installing Linux Mint Debian Edition, using the 64-bit Cinnamon version. Make sure to back up all of your files before you begin! Get Linux Mint here: http://linuxmint.com

Here's the article I used to move my /home partition to an external hard drive (only worry about this if you know what it means and you know what you're doing): https://help.ubuntu.com/community/Partitioning/Home/Moving