What's OEM software? Is it safe to buy?

If you've purchased a machine lately, there's a lot of software already installed on the machine. A good manufacturer will also provide you with the CD-ROMs containing that software, so that you can re-install it should you need to reformat or otherwise repair your machine.

OEM Versions of software are provided by the software vendors, like Microsoft, to manufacturers for mass distribution on new hardware. Sometimes there's nothing different between an OEM version of Windows and its retail counterpart. More often, though, the hardware manufacturer will customize the operating system such that in installs drives for their specific hardware, displays their logo on boot, or other things relating to that specific manufacturer. OEM versions of applications, such as Microsoft Office for example, are typically pretty much identical to the box you might pick up on a store shelf.

Folks attempting to sell OEM version of software are typically sell the backup CD-ROMs that came with machines they've purchased. They've backed up their machine in some other way, or perhaps duplicated the CDs for their own use, and are taking the "official" OEM CDs and offering them for sale.

The problem is simple: OEM software almost always includes licensing language along these lines: "For distribution with a new personal computer only. This software may not be sold independently."

Pretty clear, eh? Reselling the software that came with your computer is a violation of the software vendor's terms. In other words, it's illegal.

Another potential problem is that what's advertised as OEM software isn't that at all - it's simply illegal pirated copies of the software. The OEM term is used simply to attempt to "legitimize" the deeply discounted price.

Now, unless you yourself are building a business attempting to sell OEM software illegally, you're probably not going to get a visit from the police about this. But you could run into some very serious issues down the road. Specifically: you may not be able to update your software.

Microsoft, in particular, has been slowly ramping up their enforcement of software legitimacy. That means that if the software you're running is determined to be an OEM version that's been compromised and purchased illegally (typically determined by the product key being used by many more people than there were machines shipped with that key), you may be denied product updates, including serious security patches, until you legalize your copy. (Which is typically as simple as purchasing a retail copy and installing that on top of your existing copy.)

So my advice is simple: buy retail. Definitely go bargain hunting, but as soon as you see "OEM", run away. Buy from a legitimate retailer instead.