Brown box is (I assume) the same as "White Box" or "OEM" (original equipment manufacturer) - they basically mean that you don't get all the pretty packaging, or all the free stuff (games and programs) you'd get if you bought it Retail. Its cheaper to then the OEM, but sometimes you can get a lot of good software in the retail package that makes it worth the extra $$$. Also, sometimes the OEM's warranty isn't as long as the retail warranty. Always ask before you buy.
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