I have a fast system as well, but your not reading my problem. I would not consider seeing a person getting online on MSN as multitasking, but it still makes me lag. I have the same cpu as you but the problem still stays even if I overclock to 3.4Ghz so thats not the problem! Its a software issue in vista as it happens in both VLC and in WoW or SMPlayer. I am not running any other things in window mode Here is an exampel, having that menu open in the top makes the movie lag insanely much, closing the menu and I have no problems whatching the movie. If MSN had made a popup message saying "Dude123 has come online" It would be the same lag. Here is a few more screenshots first one is lagging like crazy second is running smooth and there its the start menu being open that causes it