Which Graphic card?

I have a MacPro and recently found a good deal on a Sharp 40" 1080p TV. I've attached it to my computer using HDMI and it works, ok. My current graphics card outputs @ a maximum of 1600X900. The Sharp HDMI setting looks better so that is what I'am using. I was wondering if I were to put in a higher resolution graphic card (2650X1900) will the picture improve (higher resolutions) or am I limited to 1920X1080?
Mahalo for any help in figuring this out.

The TV's native resolution is 1920x1080 so you're limited to that maximum resolution and getting a video card that can output more than that won't make any difference (well, it might make a bit of difference since it's presumably going to be more powerful than your current card and thus provide performance enhancements in applications that use it).

If your current graphics card truly is limited to a maximum output of 1600x900 (which on a Mac Pro I find a bit difficult to believe seeing as how even base Macbooks can support external resolutions of 1920x1200 or higher), then upgrading would probably be a good idea as you will then be able to use the TV at its native resolution of 1920x1080.

The Mac Pro can certainly output a resolution up to 2560x1900. I am willing to bet this isn't an issue with the graphics card but with the display settings either on the Mac or on the TV itself.

Mahalo for all of your responses. You've confirmed what I suspected. As a note when I go to the MONITORS preferances the highest resouloution listed is 1600X900 so I assume that is the max that the current card can display.
Thanks again.

Video card

This is the Display's window

View attachment 11784

http://www.mac-forums.com/forums/mac_images/images/attach/jpg.gif

Well, that didn't work. I thought this was a Mac friendly site, I can't even import a simple screen shot.
Anyway thanks for the responses, it did help.