There seems to be a massive confusion as to the meaning of the word 'Upgrade'
First, there is the concept: going from an older OS (XP) to a newer one (7) is an Upgrade. Regardless of what process and what version you use.
Then, there is the process. An in-place Upgrade vs a fresh install.
Finally there is the version: Upgrade vs full-retail vs OEM
Now, try to wrap your brain around following: You can use an Upgrade 64-bit version of Win 7 to Upgrade from 32-bit XP using a fresh install process. Capische? You shut down your PC, put in the Upgrade DVD, and boot up from the DVD. The setup starts, notes that you have a qualifying copy of Windows already installed on the PC, and your install proceeds exactly the same way as if you had an OEM or full retail version.
If you are a student and have a .edu email address , I believe you can still get an Upgrade copy of Win7 HP for $30. And if you got several PCs to upgrade, the Home Premium 3-licence Family Pack for $150 blows OEM out of the water.