7 will make it prettier, especially if its 64 bit, but xp will give you better performance, it really depends on what your buying, if your buying a low end budget machine I would actually go with xp to boost your performance. Ram min requirements for games double on win7 compared to xp. If you have a nice rig incoming and you play games that take advantage of directx10 and 64 bit windows def go for windows 7. This is simply because windows xp uses less ram and cpu power to operate, windows 7 takes up around 4 times more resources then windows xp(guestimation).