lo,
careful when using some advice. when playing bf2 i wanted widescreen resolution. i was told to adjust the shortcuts target so that it had my resoluton after where it said fullscreen to my native res. this will fill the screen but it is no different than unchecking maintain aspect ratio in the advanced setting of your gfx card. it merely stretches the image to the specified size. beware size of an image and resolution are completely different. i play css and dod source versions and valve have fantastic options menu's which allow all formats i.e 4:3, 16:9 and 16:10. changing resolutions makes a difference but using the other posters methods doesnt do the same thing. basically to my knowledge anyway if the game doesnt support it it wont be in the options menu. simple as.
i am not trying to insult the above poster just offering some advice which i hope helps.