I purchased to upgrade my xp 64 system.
If you are going to upgrade from a 32-bit to a 64-bit you will have to do a clean install. One way to find out is to start Windows 7 Home and put the upgrade disc in the DVD drive. It should let you know whether or not Windows 7 Home can be upgraded to Pro or not. However, you may want to consider doing a clean install. Test it first by inserting the disc and see if will allow you to upgrade. Would you be opposed to a clean install?