Yes, as Mucks says it would be wise to make a backup image first, I believe some hard disk manufacturer's websites offer free copies of re-labelled Acronis True Image, backup software which I use and has saved my bacon a few times.
If I find time I may try and install Win 7 & Mint on a test drive, just to see what's involved but I have to say it's low priority with me atm.
Good luck Boot