i know that the op's question is already answered but in case anyone browsing over here is curious about imaging here is how its done. First, you have to have an external hard drive with more free space than the size of the partition that you wish to copy. Then you boot off of the mint cd. Make sure that your external hard drive is plugged in and registered. Once you are at the main desktop screen click on Elyssa (or whichever the menu button happens to be) and then open Terminal. Once you are in terminal do the following:
1. type cd /media/ (not pressing enter at the end)
2. press tab. a menu of devices should appear. press the first few letters of the name of your external hard drive (case is important here. press tab again and press enter.
3. type the following and press enter (replace <partition> with the name of your partition eg sda2)
dd if=/dev/<partition> of=mycopy.img
It will take a very long time. once it is finished to copy it to a new computer with partition of the same size do the exact same except on step three you type
dd if=mycopy of=/dev/<partition>
remembering the replace <partition> as described above. you can also use this to copy whole hard drives (including partition table and mbr) by replacing <partition> with the hard drive eg. sda. hope this is useful to someone.