The Coupon Code is "EMCWVWX22." It expires on Dec. 16. Newegg charges Sales Tax in California, Tennessee, and New Jersey. The Windows version involved can be found here.
A few questions may come to mind. What does "OEM" mean? Why is it a specific version of Windows? Doesn't the package ship with both 32-bit and 64-bit installations? And why would anyone want Windows 7 if Windows 8.1 is already out?
Answering the last question first, quite a few people are dissatisfied with Windows 8, which tries to combine the mobile experience of Windows Phone with the desktop OS. Many people set their Windows 8 systems up to boot directly to the desktop, eschewing the Modern UI experience and Metro-style apps completely.
Meanwhile, much like Windows XP -- which, when Windows Vista was unveiled, was still desired by many -- Windows 7 is still beloved (or better loved) over Windows 8.
In terms of the other questions, to be clear, this is the OEM or system builder version of the product. As such, it contains only one version -- the 64-bit version -- of the product. The full retail version from Microsoft contains both the 64-bit and 32-bit versions. Notably, the 32-bit version of Windows 7 is also sold at Newegg, but for a different price.
This is also -- again, to be clear -- the Home Premium build of Windows 7, but it does include SP1 (service pack 1).
The details and Microsoft's stance on System Builder licenses can be found here.
The OEM or system builder version of an operating system is the sort of software that is used by Dell, HP and other laptop and PC manufacturers, and comes pre-installed on pre-built machines. It is tied to that machine and in fact, the motherboard. If the motherboard is replaced the serial number is no longer valid. Of course, if Dell were to replace the motherboard of your machine for some reason, that issue will be corrected before it is returned to you.
If, instead, you were the replace the motherboard of your home-built machine yourself, you'd have to tap-dance with Microsoft to get the serial number reactivated. Eventually, if they believe you, they will relent.
It also is not sold in "upgrade" form. That is OK for most of those opting for this option, however, since a clean install is preferred by many, eliminating the dross from the older installation of software.