Amazon lists that upgrade's cost as 69.76 USD and 79.92 USD for Home Premium to Ultimate.

You don't need to purchase Pro. I was hoping you'd take some initiative and figure it out yourself but obviously I should know better.

Here's a youtube video (since that seems so popular these days).

1. Click on this link http://www.youtube.com/watch?v=Z9kcFSOwbU8 in your web browser.
2. Perform the instructions as shown in the link in step #1.
3. Enjoy.

If you have activation issues there are ways around that as well if you take the 5 minutes to search the internet.

I was going by a recent ad from Microcenter for around $50 US for an Anytime Upgrade. I didn't pay that much attention to it as all of the copies of Windows I have are already Pro. The upgrade for earlier versions of Windows costs more, but the "Anytime" upgrades are for lower versions of Win 7 to higher and are quite a bit cheaper.