@AC - Try:
If you get stuck on Mint screen:
2.Enter Mint machine settings (in Virtualbox)
3.Enable PAE/NX at System/Processor section
Alternately, you could try my approach; which is to swear horribly; nuke the VM; and try it again, but this time reading the instructions properly. Or indeed, at all. Here's some in Instructables or YouTube flavours and even a bonus 7 Things to do after installing Linux Mint 17 (YouTube).
I wasn't being sarcastic, by the way...I enjoy seeing how far my ninja senses can take me before I have to read the instructions. And haven't actually set anything on fire yet. With Linux.