You can easily check using your existing monitor,
Download FRAPS click here
Start it and then run your games at 1280x1024 instead of 1024x768.
Fraps will display the frame rate in one corner of your monitor screen.....you can also set it to record a game session so you can see the overall frame rate included the maximum and,most importantly minimum that you get.
Don't forget you can run the tft monitor at lower than its native resolution......it just wont be as clear a picture.