This question probably has an obvious answer, however I have 2 choices in PCs to run nXt on. The first is 32 bit running XP w/ 4gb ram and AutoCAD 2010; The second is 64 bit running vista w/ 12gb ram and AutoCAD 2011. My renderings will be for output only. As with many people, I need to purchase today. Any reason not to go with the 64?