Firstly you do not buy Linux Mint as it is open source and free to download
I thoroughly recommend Linux Mint 8 Main Edition which is built upon Ubuntu 9.10 Its easy to install and easy to use plus it comes with much of the software you are likely to need preinstalled
Linux Mint 8 Download
http://www.linuxmint.com/edition.php?id=44
The Perfect Desktop - Linux Mint 8 (Helena) Installation
http://www.howtoforge.com/the-perfect-desktop-linux-mint-8-helena
Linux Mint 8 Helena User Guide
http://www.scribd.com/doc/23787138/Linux-Mint-8-Helena-User-Guide
You download the ISO. image of Linux Mint 8 then you need to create a Bootable LiveCD for installation
HowTo create a Linux LiveCD
https://help.ubuntu.com/community/BurningIsoHowto
Linux Mint 8 can also be run direct from the LiveCD from Booting up without touching your Hard Drive
Windows 7 RC1 Vs. Linux Mint 7 RC – Review (May 2009)
http://www.derick.in/247/windows-7-rc1-vs-linux-mint-7-rc-review/
LUg.