I am looking to buy a copy of windows XP Pro to run on my new mac pro for those apps that I need windows for. I have been shopping around and am having a problem. XP from a a computer store is around $300 US, I have looked on ebay which I am not very familiar with and can find "New in Box" copies for $120 US. Some say OEM while others say new full version. These sellers on ebay have a long history and seem credible. Here's the question is the OEM a full version that will work? From what I can tell the only difference is the License is tied to the machine once used. Am I asking for trouble if I don't buy the $300 dollar box? Thanks, just laid down 2500 on a new Mac machine and don't want to spend any more on windows than I have to.