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#31
As you can tell from the direction of this thread, there is no answer to that.
The best suggestion is to purchase from a reliable seller like Amazon, make sure it is shipped and sold from Amazon, not a reseller, that way you have some recourse if your key turns troublesome.
Here is one sold by Amazon,
Amazon.com: Windows 7 Ultimate SP1 64bit (Full) System Builder OEM DVD 1 Pack (New Packaging): Software
As mentioned earlier, while waiting for your key to arrive you can install using a download from here,
Windows 7 Direct Download Links, Official Disk Images from Digital River
and use and setup your system while waiting.