Questions about buying Windows 7

I am going to buy this OS, I have heard some great things about it and I had some questions. I was reading an article saying that I could buy the OEM edition of this OS and save some money. It states that I can buy the OEM editions of Windows 7 Professional and Windows 7 Ultimate at $134.99 and $174.99, respectively, 55% and 45% under the list prices of the same full editions. Now what are your all thoughts on this, would this be the route to go to save money or would I be better off buying the Retail version. What are the cons to the OEM version?

Here is the link to the article: http://www.computerworld.com/s/artic...taxonomyId=125

The article does go on to tell about the one major reason and that is that it can't be installed onto another machine, say if the one you have dies for some reason, the OS goes with it.

If I remember correctly from being in a pc shop for awhile an OEM edition also has to be sold with hardware to be at the lower cost. I know you can find websites out there that will just sell you the software but that is against MS agreement in selling OEM editions. The reason its cheaper is for system builders to be able to add windows into their builds at lower cost keeping the machines cheaper.