If you have at least 1GB or ram on your machine you may want to consider enabling the Bigger Tiles plugin.
I have found that by enabling this moving the image around the screen is much smoother and easier on the eyes. To enable the plugin go to where you have installed Photoshop on your system then navigate to:
Plug-InsAdobe Photoshop OnlyExtensionsBigger Tiles
In the Bigger Tiles folder remove the ~ character from Bigger Tiles.8BX and restart Photoshop.
(Just put the ~ back if you want to revert back)