I'm on a dual boot system.. ME and W2K. When I first got 2k, I hated it cuz it was very sensitive to mismatched ram sticks (when two or more instlled), and had tons of tcp/ip problems as well as driver problems for the joystick, etc. software didn't run either. Since then, SP2 and now SP3 has come out. Win2K is rock solid. ME, on the otherhand, is now troublesome and I occasionally have to manually delete my tcp/ip stack in the registry, and reinstall apps. My personal theory? Bugs deliberately introduced into ME to force upgrades cuz it was never like this at the beginning. But that's just my ufo conspiracy theory. So, 2k is stable, best OS that MS offers now. (better than XP for a lot of reasons). Some high end apps like Universe won't run in anything other than 2k. Most game peripherals now have 2k drivers. etc, etc. So I suspect I'll be on 2k only before long. And yes, it manages memory better than ME and norton AV does slow down ME quite dramatically. The new BlackIce 3 also interferes if you chose the application protection option. Norton doesn't work on 2k, but a cheapware called OnTrack works just fine with it. Good competetive product.