Need Help with Resolution

[Professor S]

I have had a problem with my PC for quite a while now... I can't get a lot of games to default at 800x600. Now I know thats a lower resolution, but whenever I go higher, the image does not fit my monitor.

Most recently this happened with Rome:Total War. I was able to set the battle resolution to 800x600, but my menu resolution was still much higher, making the menus very difficult to navigate as I couldn't even see much of the menu.

Can anyone help me with this, as its VERY frustrating.