Re Linux Mint 15
I have been using a dual boot system - (This one an old Dell Vostro 1310) for the last 3 Years - At install, I was given the option to "Share" My linux install with the established XP - SP3 operating System - I did this, giving Ubuntu early ver 10.04 a share of my choice with the established operating SYS XP - Ubuntu was allocated 45 Gb of the available dis space on my 160 Gb Device, the install instituted a Grub loader - and as Mix has stated; you get a choice on Start up.
Mint may "want the whole" of the primary boot drive to install properly - the Co-Exsistance that I've enjoyed is now not recommended unless you have two separate physical drives installed.
To help and I have no special attachment to Ubuntu - I use 12.04 on both an upgraded Asus one Note Book (1.5 Gb - It can be done) and a cantankerous beast of an old Dual E8200 dual core Advent (just for the fun of a challenge) in it 64 bit form, with an Invidia Graphics card, successfully so far - Gimp 2.8 Photo editing ?
Its worth persevering - You can even install an anti-virus "Comodo 64 bit " in my case or CLAMAV, in case you are exchanging media between the systems.
CAT III