MAME with vertical monitor

[deadmoney5]

I am building a MAME bartop and using a Dell LCD monitor in vertical position.  You can change the rotation in Windows so that the image is in portrait view for you.

I know you can do the same from within the MAME.ini, but I'm guessing you don't want to change that value if Windows already rotated the screen for you?

Does it matter if you make the change in Windows or within Mame itself?  Is it better to leave Windows in horizontal mode and let MAME make the rotation for the games?

[BadMouth]

It depends on whether or not you plan to run emulators other than MAME.

For MAME, the end result will be the same either way.

Having the desktop vertical will cause problems for other things like the vertical NAOMI shmups and Taito Type X games.
These are more demanding of your processor and GPU, so they might not be an option anyway.

[Howard_Casto]

Vertical cabs are a pain in the butt. 

From my experience you'll probably end up having to do both if you have a wide variety of games/emulators installed.  So use the software suite that came with your graphics card to define a vertical and horizontal profile and save a shortcut to them.  You should then be able to switch within your FE prior to launch on those problem games. 

IMHO which orientation you use by default has a lot to do with the FE you choose.  If it doesn't support rotation then obviously you'll have to rotate at the desktop level.  Otherwise letting mame do it is probably better.