big moniters are good man, ok so u have a 17inch screen at 1280x1184 or whateva and u have doom 3 running you get say 56fps on 1280x1184 or whateva then u have 50fps on 1600x1200 on a 22inch screen, i guess what i am trying to say is that theres not much differnce in frame rate of a slight increase in res and you dont get the jaggy crap around the lines
also i suppose if your worried about refrsh rated if you have a bigger screen eg 19 inch then u can a lower res but still more space on the desktop and have a higher refresh rate !
so i gues having a bigger screen kinda does help
kind regards