Software cannot actually calibrate a monitor, you need a piece of hardware. I, personally, use a Huey pro. You can buy these for about £60 if you shop around but you need something to actually read the output of the monitor in order to tell what it is actually giving out.
There are alternatives but they all basically do the same! If you live near to another TPer that has a calibrator you could always borrow theirs! I have attached my calibrator to several peoples computers in order to create a profile and they are happy with the results.