Dual monitors: Use twinview. There is no need to have xinerama enabled if you just have two monitors using twinview.
Besides with twinview you get hardware accelerated graphics.
Three monitors: Have two of them with twinview and one separate screen. All of them with xinerama disabled.
Workarrounds for the meantime:
Dual monitors: Use twinview. There is no need to have xinerama enabled if you just have two monitors using twinview.
Besides with twinview you get hardware accelerated graphics.
Three monitors: Have two of them with twinview and one separate screen. All of them with xinerama disabled.