If you have intergrated graphics, right click on "My Computer", and select "Properties", click on the Performance tab. Click the Graphics button at the bottom, and set it to basic or none. It should help.
Yeah, I just upgraded my hard drive to a much faster one and it makes such a big difference. I don't think the size matters as much as how quickly the data can be pulled off the drive. However, it's a real pain re-install and copy across all my characters and objects.
