OEM = "Original Equipment Manufacturer", as in the CD provided by Gateway, Dell, Compaq, etc. Retail is just as it sounds. A retail version that is not offered via 3rd party. Sometimes OEM may have additional things added, but not likely. The biggest difference you will see between OEM and retail is in the EULA. The OEM EULA depends on the agreement between MS and said company. Just do a google for retail EULA and what ever OEM EULA to find the difference. Also, you can purchase extra liscense from MS for multiple systems without needing another CD. Just contact them.
If you argue with an idiot he will drag you down to his level and beat you with experience.
I am not a fast writer.
I am not a slow writer.
I am a half-fast writer.