Here's my XF86Config-4 as it is now:
Code:
Section "ServerLayout"
	Identifier     "XFree86 Configured"
	Screen      0  "Screen0" 0 0
	Screen      1  "Screen1" LeftOf "Screen0"
	InputDevice    "Mouse0" "CorePointer"
	InputDevice    "Keyboard0" "CoreKeyboard"
EndSection

Section "Files"
	RgbPath      "/usr/X11R6/lib/X11/rgb"
	ModulePath   "/usr/X11R6/lib/modules"
	FontPath     "/usr/X11R6/lib/X11/fonts/misc/"
	FontPath     "/usr/X11R6/lib/X11/fonts/Speedo/"
	FontPath     "/usr/X11R6/lib/X11/fonts/Type1/"
	FontPath     "/usr/X11R6/lib/X11/fonts/CID/"
	FontPath     "/usr/X11R6/lib/X11/fonts/75dpi/"
	FontPath     "/usr/X11R6/lib/X11/fonts/100dpi/"
EndSection

Section "Module"
	Load  "dbe"
	Load  "dri"
	Load  "extmod"
	Load  "glx"
	Load  "record"
	Load  "xtrap"
	Load  "speedo"
	Load  "type1"
EndSection

Section "InputDevice"
	Identifier  "Keyboard0"
	Driver      "keyboard"
EndSection

Section "InputDevice"
	Identifier  "Mouse0"
	Driver      "mouse"
	Option	    "Protocol" "auto"
	Option	    "Device" "/dev/mouse"
EndSection

Section "Monitor"
	#DisplaySize	  320   240	# mm
	Identifier   "Monitor0"
	VendorName   "VSC"
	ModelName    "A70"
	Option	    "DPMS"
EndSection

Section "Monitor"
	Identifier   "Monitor1"
	Option	"DPMS"	"true"
	VendorName	"IBM"
	ModelName	"IBM08bb"
	HorizSync 30 - 54 # DDC-probed
	VertRefresh 50 - 120 # DDC-probed
	# These are the DDC-probed settings reported by your monitor.
	# 1280x1024, 75.0Hz; hfreq=79.98, vfreq=75.03
	ModeLine "1280x1024"	135.00 1280 1296 1440 1688 1024 1025 1028 1066 +hsync +vsync
	# 1024x768, 75.0Hz; hfreq=60.02, vfreq=75.03
	ModeLine "1024x768"	 78.75 1024 1040 1136 1312  768  769  772  800 +hsync +vsync
	# 800x600, 85.0Hz; hfreq=53.67, vfreq=85.06
	ModeLine "800x600"	 56.25  800  832  896 1048  600  601  604  631 +hsync +vsync
	# 800x600, 60.0Hz; hfreq=37.88, vfreq=60.32
	ModeLine "800x600"	 40.00  800  840  968 1056  600  601  605  628 +hsync +vsync
	# 640x480, 85.0Hz; hfreq=43.27, vfreq=85.01
	ModeLine "640x480"	 36.00  640  696  752  832  480  481  484  509 -hsync -vsync
	# 640x480, 75.0Hz; hfreq=37.50, vfreq=75.00
	ModeLine "640x480"	 31.50  640  656  720  840  480  481  484  500 -hsync -vsync
	# 640x480, 60.0Hz; hfreq=31.47, vfreq=59.94
	ModeLine "640x480"	 25.17  640  648  744  784  480  482  484  509 -hsync -vsync
EndSection

Section "Device"
        ### Available Driver options are:-
        ### Values: [i]: integer, <f>: float, <bool>: "True"/"False",
        ### <string>: "String", <freq>: "<f> Hz/kHz/MHz"
        ### [arg]: arg optional
        #Option     "NoAccel"            	# [<bool>]
        #Option     "SWcursor"           	# [<bool>]
        #Option     "Dac6Bit"            	# [<bool>]
        #Option     "Dac8Bit"            	# [<bool>]
        #Option     "DMAForXv"           	# [<bool>]
        #Option     "ForcePCIMode"       	# [<bool>]
        #Option     "CCEPIOMode"         	# [<bool>]
        #Option     "CCENoSecurity"      	# [<bool>]
        #Option     "CCEusecTimeout"     	# [i]
        #Option     "AGPMode"            	# [i]
        #Option     "AGPSize"            	# [i]
        #Option     "RingSize"           	# [i]
        #Option     "BufferSize"         	# [i]
        #Option     "Display"            	# <str>
        #Option     "PanelWidth"         	# [i]
        #Option     "PanelHeight"        	# [i]
        #Option     "ProgramFPRegs"      	# [<bool>]
        #Option     "UseFBDev"           	# [<bool>]
        #Option     "VideoKey"           	# [i]
        #Option     "ShowCache"          	# [<bool>]
	Identifier  "Card0"
	Driver      "ati"
	VendorName  "ATI Technologies Inc"
	BoardName   "Rage 128 PD/PRO TMDS"
	BusID       "PCI:1:11:0"
EndSection

Section "Device"
        ### Available Driver options are:-
        ### Values: [i]: integer, <f>: float, <bool>: "True"/"False",
        ### <string>: "String", <freq>: "<f> Hz/kHz/MHz"
        ### [arg]: arg optional
        #Option     "NoAccel"            	# [<bool>]
        #Option     "SWcursor"           	# [<bool>]
        #Option     "ColorKey"           	# [i]
        #Option     "CacheLines"         	# [i]
        #Option     "Dac6Bit"            	# [<bool>]
        #Option     "DRI"                	# [<bool>]
        #Option     "NoDDC"              	# [<bool>]
        #Option     "ShowCache"          	# [<bool>]
        #Option     "XvMCSurfaces"       	# [i]
	Identifier  "Card1"
	Driver      "i810"
	VendorName  "Intel Corp."
	BoardName   "82810E DC-133 CGC [Chipset Graphics Controller]"
	BusID       "PCI:0:1:0"
EndSection

Section "Screen"
	Identifier "Screen0"
	Device     "Card0"
	Monitor    "Monitor0"
	DefaultDepth 24
	SubSection "Display"
		Depth     1
	EndSubSection
	SubSection "Display"
		Depth     4
	EndSubSection
	SubSection "Display"
		Depth     8
	EndSubSection
	SubSection "Display"
		Depth     15
	EndSubSection
	SubSection "Display"
		Depth     16
	EndSubSection
	SubSection "Display"
		Depth     24
	EndSubSection
EndSection

Section "Screen"
	Identifier "Screen1"
	Device     "Card1"
	Monitor    "Monitor1"
	DefaultDepth 24
	SubSection "Display"
		Depth     1
		Modes "1024x768" "800x600" "640x480"
	EndSubSection
	SubSection "Display"
		Depth     4
		Modes "1024x768" "800x600" "640x480"
	EndSubSection
	SubSection "Display"
		Depth     8
		Modes "1024x768" "800x600" "640x480"
	EndSubSection
	SubSection "Display"
		Depth     15
		Modes "1024x768" "800x600" "640x480"
	EndSubSection
	SubSection "Display"
		Depth     16
		Modes "1024x768" "800x600" "640x480"
	EndSubSection
	SubSection "Display"
		Depth     24
		Modes "1024x768" "800x600" "640x480"
	EndSubSection
	SubSection "Display"
		Depth     32
		Modes "1024x768" "800x600" "640x480"
	EndSubSection
EndSection
I don't have any resolutions configured for Screen0, but Screen1 is the one giving me trouble. I used the device configurations reported to me by the Knoppix CD for Card0, Card1, Monitor1, and Screen1, and the X -configure settings for Monitor0 and Screen0 (and everything else). I also double-checked, and my Screen1 is running at 800x600, not 640x480 as I previously thought. I just looks really low because the other screen is running at 1280x1024. Whoops... scratch that. The other screen is running at 1400x1050 (yikes).

By the way, sometimes I screw up the XF86Config-4 file and get two blank screens when I restart X. Is there a keyboard shortcut I can use to get into text/command-line mode from there?