You didn't say what kind of cpu you had. I had Vista with a 1.6 GHz cpu and from the event logs, my virus scanner was a problem and Windows Explorer as well. Also if you did an upgrade there may be a lot of files left on your system which can cause a problem. You have to be careful about their removal though and I'm still looking for straight answers about a lot of them. Also as someone mentioned in Vista you can check what is running when you start-up and if you don't need it as soon as you turn on your pc then disable it. Just start it when you need it.