Chosen Solution

I want to move an internal hard drive from my old Windows XP machine and install it into my new Windows 7 machine. No system files are on the hard drive, just data.

That should work fine. The only issue is is that it might be an IDE drive and your newer machine will most likely only have SATA connections. Pull out the old drive and look to see what connection type it has if it’s sata you should be able to transfer it to the Windows 7 machine, boot it up and see it as an available drive with the data on it.