Ive got the laptop connected to the TV with an HDMI cable (HDMI output on both items), everything is great apart from the picture on the TV is to wide, the TV wont let me change the size and the laptop is Vista which ive not got a scooby how to use.

How do i go about changing the screen size, also how do i make the screen saver/desktop stay off (when im watching anything it comes up every 10 mins).