Couple of things to check. First make sure you install all the updates. Vista is still full of bugs. Then keep in mind that vista uses much more RAM then XP. Something like 600+ meg minimum. So check the size of your swap file and your hiberfile. Increase swap file to be at least the size of RAM. And you may want to disable hibernation, then reboot, then re enable it, because I assume you did an upgrade and I am not sure if it's set up correctly. Not sure if this will help, but this is what I would do first.