change AR of monitor to 4:3

[NeoFiren]

hi guys,
I have a dell s2009W whose aspect ratio is 16:9...
I'm able to play all the new games like crysis and NFS in 16:9 resolutions (1600*900).But some old games don't run in widescreen and appear stretched.
Is there any way I can change my monitor's ratio to 4:3, so that it doesn't stretch in 4:3 resolutions like 1200*900...
thnx!

[Mario2]

I think that old games dont support that kind of resolution, what are they, can you name a few? You should start by looking at the Master Games List, which is linked to in several places - List of games with widescreen support. If a game has an .ini solution that allows you to specify the resolution you should be good.