you have a 19" monitor and it cant do 1600x1200? What brand is it.
By the way upgrading your graphics card wont effect much. You already have a nice enough card to display things. Its Intel IGP's that you have to worry about. Any ATI Nvidia card that was made the last three years or so should perfectly fine on any nice montitor out today.
I personally have a 17" running at 1280x1024 its at 60htz and it looks really nice. When i bump it down to 1024x768 things just look aweful. Everything is so big. How can you look into 19" of splendor at 1280x1024.
Also most semi nice 19" run optimally at 1600x1200 so things might look better at that resolution.