Xinerama, xrandr, fglrx - what is the deal

[Bruners]

What happens with those games?

Also, you can make those xrandr changes permanent in your xorg.conf file instead of adding it to your .xinitrc, if you want. You would need two monitors sections, one with the Identifier DFP1 and one with the Identifier CRT1. Something like:

Section "Monitor"
        Identifier "CRT1"
        Option "RightOf" "DFP1"
        Option "PreferredMode" "1440x900"
EndSection

Section "Monitor"
        Identifier "DFP1"
EndSection

Turns off the second monitor when the game starts, currently the only game I care for is Heroes of Newerth and it doesn't support xrandr, yet.

[rohcQaH]

most games don't run well on multiscreen-resolutions anyway. You can however try setting the game to windowed mode and force it into a fullscreen, borderless window. (kwin's application specific rules come to mind, but use whatever your window manager supports)

[WhiteDwarf]

Turns off the second monitor when the game starts, currently the only game I care for is Heroes of Newerth and it doesn't support xrandr, yet.

A RandR 1.2 modesetting backend is coming to the next version of HoN (Just be warned that ATI's RandR 1.2 support has a number of bugs and you may encounter one or two).