Best answer i have found so far with the differences between the windows 7 upgrade and the full retail versions.
Aside from those differences stated above, there is no difference between the upgrade and full versions of the same edition. Both contain the same software packages and functionalities without any type of limitation for the cheaper upgrade version. The only difference is in the small portion of code that checks for the presence of a previous Windows installation; added to the upgrade version installer and doesn’t affect the operating system once it is installed
And there is this small note from that article:
This behavior of the upgrade version can be a problem or at the very least an annoyance to those who often reinstall their operating system or even to ordinary users who experience computer troubles. Reinstalling the upgrade version would mean that you would also need to reinstall your older version of Windows and have it activated before you can install Windows 7. This adds an extra step to the already long process of installation and not to mention the need to keep the both discs and serial numbers safe as losing either would be a very big problem.
Now i do not know for sure but from the looks of this information your upgrade version must then reflect your old os (xp or vista) whether it was oem or not as it would need to be installed and activated before you could reinstall the windows 7 upgrade again. So for those who like to replace hard drives as well as do fresh new reinstalls of an os from time to time an upgrade version seems to be a pita.
So if you like to replace hdd drives or ssd drives occasionally your choices are:
1. buy the upgrade and to keep your old windows xp and vista discs and keys to install the upgrade version (if your old os was an upgrade from a previous os then you would need those discs and keys as well) so if you upgrade your dell or (insert name brand pc manufacturer here) and need to replace your hdd later you are out of luck on being able to use the upgrade disc again.
2. ignore the tos of windows and buy the oem version (note: it is meant for people who build pc's to resell not for diy pc builders or for people who want a cheaper alternative to the full version price) And basically be pirating as you are not supposed to be given a copy of the oem disc with your build. (another note being that this is tied to your motherboard so if you upgrade you are supposed to buy another oem for that upgrade)
3. buy the full version and install it on any machine configuration you wish provided it is only installed on one machine at any given time (meaning only one pc can be using the key for your full version at any given time) if you want to install it on more then one pc you need to purchase an additional key for each of the pc's you want to install it on
It be nice if this information was made more clear (and microsoft was more consistent). As stated even people who work for microsoft buy and use the oem version over the full version not only for their pc's but also for family and friends pc's. Many people still continue to buy the oem versions for diy builds despite its user agreement (very few people read through it). People using the oem version installs are more often then not still getting their oem keys reactivated (and microsoft has even given new keys to pirated installs of their os) even if they upgrade and even if they upgrade their motherboard to a different brand. In most cases all you need to do is to call them.
Now i am in no way advocating piracy or ignoring the end user agreements of microsofts os. But do find it funny that many times people pirate their os and microsoft does not take the time to verify it and reactivates the pirated os and at times even gives them new keys. And despite their user agreement on the oem versions often reactivates them as well as issuing new keys for those as well. Some pirate os got their keys by going to a place that sells pc's and copying the windows key from the side of the machine setup as a display model (so i do not recommend any one ever buying the display model pc at all at your local stores).
Just thought people should be informed on whats going on around them. I do not recommend pirating as if caught you will more then likely face severe fines and maybe jail time. And i do not recommend the oem version because even if they are at times still activating them for upgrades and such that does not mean it will always happen (and the cost of 1 full version is a lot cheaper then the 2 oems you would be purchasing any way if they refuse to rectivate your windows). So it seems the 2 best options are the upgrade (with the added pain of installing your old os before the upgrade) and the full version (it is by far the most flexible of all the options on reinstalls and upgrades).
I do find this funny though :
For DIY System Builders
Building Your Own Computer?
Check out Amazon's System Builder Software Store for all your Do It Yourself PC-Building needs. Featuring the latest Microsoft OEM software, you'll be up and running and enjoying the ultimate Computer in no time.
Now here is a link to the oem of windows 7 64 bit from amazon:http://www.amazon.co...X3QMNXY2MTSBYGP
Now scroll down to the product description:
From the Manufacturer
Use of this OEM System Builder Channel software is subject to the terms of the Microsoft OEM System Builder License. This software is intended for pre-installation on a new personal computer for resale. This OEM System Builder Channel software requires the assembler to provide end user support for the Windows software and cannot be transferred to another computer once it is installed. To acquire Windows software with support provided by Microsoft please see our full package "Retail" product offerings.
If you are not careful you could easily over look that. Especially when it is advertised as
Windows 7 Home Premium SP1 64bit (Full) System Builder DVD 1 Pack
microsoft put out a memo to all places that sell oem discs to include that bit about this version only to be used in a new build meant for resell. Yet as you can see it is still put in places for do it yourself builders and marketed as such despite it clearly stating that it is only to be installed on a pc for reselling. Microsoft does not seem to be actively pushing the issue if they were one would think they would get after places like amazon pushing it as a do it yourself os. But who knows for sure as the user agreement at times conflicts with its own information.http://www.microsoft...bid=6CK-V9Obmmy
I personally recommend the full version http://www.amazon.co...=windows 7 home
$175 but compare it to buying 2 oem at roughly 91 bucks a piece $182. Yes you may pay a bit more now but you are also more easily covered for further upgrades in the future. Plus you have to keep in mind microsoft does not want diy pc builders to buy the oem version and have it clearly stated that it is for pc's in which you intend to resell. So quite a few things to keep in mind when buying an operating system. The upgrade version is also a choice provided you already have a windows os install disc and key (vista or xp).http://www.amazon.co...=windows 7 home
or go with a 3 pack to save some cashhttp://www.amazon.co...=windows 7 home