For example in the game Deus Ex: Human Revolution it allows me to play on 800 x 600 but maintain an aspect ratio of 16:10. This really helps when plugging my laptop up to the 24 Inch Monitor to read the text.

Any help would be appreciated

When you open steam , click "play" the screen that comes up..Select "Options" then you will see....

GPU
Aspect Ratio<<<< Has Standard, 16:9, 16:10
Resolution
Antilasing
Ansiotropic Filtering

Hope this helps....

Hi yes I have seen that, it does not do what I want it to do though. when i change that it shows higher resolutions.

I want to be able to play in 800 x 600

WITH an aspect ratio of 16:10

He wants to display a 16:10 letterbox @ 800x500, on a 800x600 screen. There's no such an option, unless you go windowed mode.

Try forcing it through SkyrimPrefs.ini -should work...

did not see an option for it

You could try this....in game launcher set it to 16:10. close that.

In the Skyrimpref.ini we have these lines...

bFull Screen=1
iSize H=1080>>>make this 600
iSize W=1920>> 800

Change to what you want ...i dont see a place to change aspect in the INI . Try changing the Screen size and see if the launcher keeps your choice of Aspect . i would guess it wouldn't , and or just stretch things to ugly proportions.

Full screen is a Boolen so change to 0 gets you a window. Might help?..

Basically 800x600 is not 16:10
It is 16:12 (or 4:3).
Whatever resolution you select defines your aspect ratio...
I mean, there's no such thing as 800x600 in different aspect ratios unless your monitor can 'stretch' it (but round things will become egg-shaped).