Hello Klaatu2,
I think what you really want to know is can you safely triple-boot with Windows7, Linux mint and Ultimate Edition choosing between each at start-up, If so, the answer is yes!
U. E. will safely resize your existing partitions for you by installing alongside. You don't need to do it manually.
I have four Linux distros on one HD and two on another-no problems.
Only thing you need to know is that on installing Ultimate Edition it will become the first OS to boot in GRUB unless you manually change the MBR.Whatever Distro is last to install becomes the first in the boot-order.
On the other hand, I agree with Admin-Amir, once you try Ultimate Edition you probably won't want to bother with Linux-Mint anyway, so it can be safely deleted either before or after installing Ultimate Edition Bottom line is you can keep Linux-mint if you want to and you are NOT going to lose any files or anything. My advice is until you are more comfortable with both using Linux and the pros and cons of file-compatibility is to choose triple-boot. Just let the Ultimate Edition installer do the work for you, though bear in mind Ultimate Edition has a lot more programs than Linux Mint so will take longer to install.Once it's installed however everything will be fine. I was once in your position, hesitant about deleting Windows, but within six months of discovering Linux it was gone -permanently . Good luck, and just hold on to Windows for a while till everything feels " right".
All that I am or seem is but a dream within a dream.