According to Computerworld, although you might be breaking the rules by buying and installing a Vista upgrade on a computer, Microsoft is tacitly approving the move, mainly because it helps Microsoft to please its own bean counters.
To make things even more complex, Brian Livingston, a writer at Windowssecrets, remarks that several hints inside Vista itself point to the obvious : that the trick was incorporated by Vista's developers themselves - whether they took on themselves or whether that came up in the chain of command is unknown.
A quick look at the full version of Vista Ultimate SP1 shows that it is on sale at £351.48 at Amazon while the Upgrade DVD costs much less at £199.99, a significant saving of nearly £155.
This is a much more popular loophole that has been largely exploited as the only requirement to benefit from OEM (original equipment manufacturer) prices is to purchase a piece of computer hardware like this sound card which costs £4.99.
While officially, Microsoft has stressed that OEM software is not intended to be installed by end users, behind closed doors and off record, Microsoft will not oppose the practice.

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