You could just have your windows partition automount every time you start Mint. It's not ideal, but you can move stuff back and forth. The way I've outlined below will be easier assuming that you don't have issues with NTFS.
Your best bet is to create 2 NTFS partitions. One for Windows and one for the shared data. Then just do the normal install for Mint. I like having a separate /home partition. Also, use GPT instead of MBR.
You can partition your disks with Gparted from the Mint LiveUSB (seriously, don't use a DVD unless you have to. USB is much faster), install Windows, then install Mint.
There are plenty of tutorials on the web for moving the Windows data folders to a different partition. There are also several for how to do this with Ubuntu/Mint. You can do both of these after install. Just get both of your systems working correctly, then work out your data partitions. Don't put all of your data on the system until you have the shared partition working.
To make it simple, start Gparted from the liveUSB. Make 6 partitions.
1) First partition 1MB. DO NOT FORMAT! Add the "bios_grub" flag. http://en.wikipedia.org/wiki/BIOS_Boot_partition
2) Make 2 NTFS partitions. One for windows, one for your data.
3) Make 2 EXT4 partitions. Set the mount points to '/' and '/home' There are options for this in the pull-down menu.
4) make a SWAP partition (optional, but nice to have sometimes)
You'll have to figure out how large you want each of these partitions. I would make the NTFS data partition the largest (300+ GB). My '/' partition is only 15GB, and I have about 9GB free. When I was doing a SSD/HDD build for someone, I gave windows the whole 60GB SSD, and put all the user data on the HDD. I think Windows 7 only needs about 15GB for the base install, but you will want more room than that. No clue about Windows 8.
I also prefer a straight SSD. TigerDirect has/had a deal on a 240GB SSD for right around $0.50 USD/GB.