Running Vista 64 Ultimate for great justice. And so I can use all of my ram. I avoided Vista for quite some time, but it's honestly not that bad. Couple of hours of fighting with it, now it knows who's boss, and doesn't cry at me every 10 minutes because I don't have AV software, or UAC is off. With a midrange machine the resources vista eats aren't as noticable. Mine idles with 1% of each core used, and about 800MB of RAM, and I haven't overclocked anything yet. The fix to dual view was a big plus, and I wanted DirectX10 to be an option.