you probably want to stick to something that's the correct aspect ratio for your monitor.
1024x768 is a 4:3 resolution. the next larger size supported is 1152x864.
if you have a 16:9 monitor you may be in trouble for a low res. looks like 1280x720 isn't suported, nor is 1600x900 which leaves you at 1920x1080 i think.
for 8:5 monitors, 1280x800 is fairly low and is supported. next higher res is 1400x900 which is also supported.
Looking though the list, i'm actually surprised how spotty the 16:9 support is and how good the 4:3. Good for me with my antique crt i guess, not good if you have a shiny new widescreen lcd and bad graphics hardware driving it. Also would have been so much easier if they let you set the refresh rate and resolution independently so each entry wasn't listed like 5 times.
The difference in pixels between 1024x768 and 1280x800 is negligible, so if either is correct for your monitor you should go with that one. If you have a 16:9 moniter, you might need to try 1280x800. i think it'll be the least distorted incorrect ratio, and much easier on your card than 1920x1080. 1280x720 is the res you would want to run but it isn't supported unless i missed it in the list. maybe their ui needs a min height of 768 or the scaling breaks? Or maybe its just bad 16:9 support