Say that I'd recently purchased 10 PCs from a retailer, but ordered them without any OEM operating systems, am I then at a later date allowed to go back to the same retailer and purchase 10 copies of OEM Windows, and legally install them on those PCs, or can I only legally use OEM copies of Windows that were purchased at the same time as the computer?
I would have thought I couldn't do this after the event, but if that is the case, why do many retailers (including big companies such as Dell) allow consumers to purchase OEM copies of Windows via their website without purchasing any hardware at the same time?
If there are any constraints, (e.g. you only have a limited time in which you can do this), what are they?
Edit: Additional Background Info (although, this makes the question more suitable for SF now)…
I'm about to enter a Microsoft Open Value Licensing Agreement, but all the OS licenses available under OVL are upgrade only. So I either go back to the supplier (Dell, as it happens) and purchase OEM copies, or I purchase the cheapest retail OS I can find that I can legally upgrade to Windows 7 Pro. I expect I can get OEM copies cheaper, but I need to ensure that whatever option I choose, that the business is license compliant.
Best Answer
I work for an MS OEM, so I'll share my understanding of this according to our experiences, including selling single OEM copies without hardware. Hopefully it'll make sense. ;)
As an OEM you can sell the OEM version as part of the system sold up to 30 days after the hardware has been sold (to help avoid "whoops I forgot to order Windows with this" scenarios). So even though it was sold after the fact, it still becomes 'part of the system' and the OEM who sold you the equipment will be taking on the responsibility of supporting that OEM copy of Windows.
You have always been able to buy OEM packs of Windows as an 'end-user' without hardware, but they used to only come in like 10 and 30 packs, so most end-users wouldn't buy those packs. More recently (last couple/few years) they (MS) started producing a "1-pack" so that it became more attractive to small OEMs.
The thing is, when you buy a single OEM copy like that (or a 10 pack, etc.) it will be sealed, and by breaking that seal you agree to become the "OEM" supplier for that copy of Windows, and are responsible for supporting it yourself (ie: no free MS help if you have problems), and ensuring it's legally distributed (if you resell it).
One of our hardware customers is a large university and so we deal with Open Volume Licensing quite a bit, and since it requires a preexisting OS they (currently) buy 7 Home Basic OEM with their machines as it's the cheapest, and it can legally be used as the base OS to upgrade to the OVL Windows 7 version.
So we sell it to them with Home Basic, but we install Enterprise for them before delivery as an extra service. 'Home' never actually touches the hardware (aside from the OEM stickers, which we HAVE to apply by the OEM re-sale rules). And this procedure has all been blessed by Microsoft. :)
Anyway, if you bought the machines less than 30-days ago you should be able to go back to the OEM and get the order 'amended' or alike to include the OEM copies of Windows. But since you are just replacing the OEM license with OVL, you might as well just buy a 10-pack and call yourself the OEM. :)
Hope that helps...