Dual Monitor setup under X w/Redhat 6.x

Any quick tips/links/faqs in setting up dual monitors/extended desktop under
Linux? I’ve got it going under Win98 w/o much issue, but the various X configurators -always- latch onto my PCI graphics card vs. my AGP (this in fact is a real problem ifI “blow up” my X setup – I have to pull the PCI out of the system to resetup). I admit I’m still a bit of a newbie in Linux, but I’m told this can be done. Even some sample config scripts could be helpful!