I ordered parts for my new system this weekend and it should be here anyday. I was wondering which operating system I should run on it. I am mostly going to be using the computer for some gaming (nothing too extreme), running some applications for my engineering courses in school (things like CAD, MatLab, Lab View, etc), and just all around general purposes. I can aquire a copy of XP Pro SP3 or Vista Ultimate SP1 from my school for free. Both are 32-bit. I was wondering which one I should go with or if it really even makes a difference. Would it be at all to my advantage to scrap the 32bit systems and go buy a 64bit?