Can't Get Higher Resolution

[bdm56]

Hey guys, I just beat HL2 and had a great time doing so. After I beat it I decided to crank all my graphics settings as high as they would go and play around with the game to see if it would still run smoothly, but for some reason I'm not given the option to turn my resolution higher than 1024x768. Is this normal? How to I turn up my resolution in the game?

[giant384]

depends on ur video card and monitor thats the highest u can go but i think with the 6800 cards u can have 1600x1200