I don't have any experience with Mint, but it's based on Ubuntu so this might help. In Ubuntu, you can get a package in synaptic called unetbootin. Search for that in your package manager (synaptic as well?) and download it. unetbootin is a GUI program that automates installation of an ISO file to a usb flash drive. This will take care of making a standalone usb drive of Mint (and many other distros). I think this is what you're after? (I found your post a bit unclear).
If you want to fix the GRUB bootloader on your hard drive so that it will standalone boot - Boot up your live CD and enter a terminal. Enter the GRUB shell
then locate the partition that you want the big bit of GRUB to setup on with
You'll get a value back like (0,1). Use the value you find for the next line
then setup GRUB on the MBR of your first hard drive
Reboot and hopefully everything will be the way you want.
EDIT I'm assuming with this advice that Windows is on the first partition of the first hard disk. If not, it's more complicated. Post back if you have any problems
ANOTHER EDIT Nice video of unetbootin from youtube here