Cannot open Photo shop PS3 enterprise edition on to windows 7

I’ve got a Sony laptop with Windows XP on it. I recently ran the Windows Vista Upgrade Adviser, and it said I should download Business. But my school only has Vista Enterprise for download.
Is there a difference between the two, Business & Enterprise?
Or can my laptop download Enterprise without any problems?

Also, should I download all the drivers for the laptop onto a USB first, just in case?

Two days ago I was on my computer when it hung up. I restarted it and found that Vista Enterprise which I got for free from a MSDN subscription has a time limit on it in which you have to buy a new license when it expires (it expired like three or four monthes after installing it) which is not the same with Vista Home. I was wondering if Vista Business expires just like Vista Enterprise. Also any information about the differences between the two would be greatly appreciated.

I have a legitimate copy of Vista Enterprise, and a legitimate serial key. I was wondering what the maximum amount of installs I can do on different computers.