Well, 32 bit is less efficient at a lot of stuff, and 64 bit is better.
It's a "Legal" upgrade, but it won't "Run" from the installer.
The problem is on windows part for not building a clean method of upgrading.
That aside, the download comes in a set of 3 peices, and is just a folder of the install.
I was going from vista x32 to windows 7 pro x64, pain in the arse.
The download itself won't extract on a 32 bit system that I know of, so I had to copy the files to a spare machine running xp 64, which miraculously not only could extract but offered a direct upgrade via the installer.
Wrong system, but anyways the custom install instructions require an ISO or bootable, so i ended up having to download Windows AIK (Automated Installation kit), which was another 2 gigabytes, installed that, ran a command line that turned the files into an ISO (seriously google is awsome), then I used the microsoft utility to put the ISO onto a bootable Flash Disk (USB).
Did the install, low and behold when through but wouldn't accept the upgrade key.
Called microsoft tech support, they had this to say:
HK_LOCAL_MACHINE/SOFTWARE/MICROSOFT/WINDOWS/SETUP/OOBE
I changed the value of MediaBootInstall to 0 (It was set to 1)
Then I had to run the command prompt AS ADMINISTRATOR (very important):
cd \windows\system32
cscript.exe simgr.vbs -rearm
After running those 2 lines, I rebooted. I was able to register my product key no problems.
Not sure if this helps anyone else, but yeah, that downloadable distribution blew.
**EDIT** - With those changes, I'd imagine it opens a number of possibilities with downloadable ISO's or using a friends disk. Good luck to ya.
***EDIT*** - It appears someone already posted the instructions to make a bootable here:
http://www.sevenforums.com/tutorials/30470-make-bootable-iso-student-d-l.html#post320334