can't get desired xorg resolution with FreeBSD 7.0

I have a laptop with a Radeon Mobility card on which I've been running
FreeBSD 6.2 with Xorg 7.2 using a 1024x768 resolution. On a different
slice of the same laptop, I installed FreeBSD 7.0/Xorg 7.3. With the same
xorg.conf, X is coming up with a 1400x1050 resolution, which is too fine
for my eyes.

A google search led me to think that setting the desired resolution could
be done using xrandr, but the command:

xrandr --fb 1024x768

gives an error message:

xrandr: specified screen 1024x768 not large enough for output LVDS \
(1400x1050+0+0)

The contents of /etc/X11/xorg.conf:
-----------------------------------
Section "ServerLayout"
Identifier "X.org Configured"
Screen 0 "Screen0" 0 0
InputDevice "Mouse0" "CorePointer"
InputDevice "Keyboard0" "CoreKeyboard"
EndSection

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

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

Section "InputDevice"
Identifier "Keyboard0"
Driver "kbd"
EndSection

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

Section "Monitor"
Identifier "Monitor0"
VendorName "Monitor Vendor"
ModelName "Monitor Model"
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 "BusType" # [<str>]
#Option "CPPIOMode" # [<bool>]
#Option "CPusecTimeout" # <i>
#Option "AGPMode" # <i>
#Option "AGPFastWrite" # [<bool>]
#Option "AGPSize" # <i>
#Option "GARTSize" # <i>
#Option "RingSize" # <i>
#Option "BufferSize" # <i>
#Option "EnableDepthMoves" # [<bool>]
#Option "EnablePageFlip" # [<bool>]
#Option "NoBackBuffer" # [<bool>]
#Option "PanelOff" # [<bool>]
#Option "DDCMode" # [<bool>]
#Option "MonitorLayout" # [<str>]
#Option "IgnoreEDID" # [<bool>]
#Option "UseFBDev" # [<bool>]
#Option "VideoKey" # <i>
#Option "MergedFB" # [<bool>]
#Option "CRT2HSync" # [<str>]
#Option "CRT2VRefresh" # [<str>]
#Option "CRT2Position" # [<str>]
#Option "MetaModes" # [<str>]
#Option "MergedDPI" # [<str>]
#Option "NoMergedXinerama" # [<bool>]
#Option "MergedXineramaCRT2IsScreen0" # [<bool>]
#Option "DisplayPriority" # [<str>]
#Option "PanelSize" # [<str>]
#Option "ForceMinDotClock" # <freq>
#Option "RenderAccel" # [<bool>]
#Option "SubPixelOrder" # [<str>]
#Option "ShowCache" # [<bool>]
#Option "DynamicClocks" # [<bool>]
Identifier "Radeon Mobility"
Driver "ati"
VendorName "ATI Technologies Inc"
BoardName "Radeon R250 Lf [Radeon Mobility 9000 M9]"
BusID "PCI:1:0:0"
EndSection

Section "Screen"
Identifier "Screen0"
Device "Radeon Mobility"
Monitor "Monitor0"
DefaultDepth 24
SubSection "Display"
Viewport 0 0
Depth 1
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 4
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 8
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 15
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 16
EndSubSection
SubSection "Display"
Viewport 0 0
Depth 24
Modes "1024x768" "800x600"
EndSubSection
EndSection

-----------------------------------

Running xdpyinfo gives the following data:

name of display: :0.0
version number: 11.0
vendor string: The X.Org Foundation
vendor release number: 10400000
X.Org version: 1.4.0
maximum request size: 16777212 bytes
motion buffer size: 256
bitmap unit, bit order, padding: 32, LSBFirst, 32
image byte order: LSBFirst
number of supported pixmap formats: 7
supported pixmap formats:
depth 1, bits_per_pixel 1, scanline_pad 32
depth 4, bits_per_pixel 8, scanline_pad 32
depth 8, bits_per_pixel 8, scanline_pad 32
depth 15, bits_per_pixel 16, scanline_pad 32
depth 16, bits_per_pixel 16, scanline_pad 32
depth 24, bits_per_pixel 32, scanline_pad 32
depth 32, bits_per_pixel 32, scanline_pad 32
keycode range: minimum 8, maximum 255
focus: window 0x60000d, revert to PointerRoot
number of extensions: 34
BIG-REQUESTS
Composite
DAMAGE
DEC-XTRAP
DOUBLE-BUFFER
DPMS
Extended-Visual-Information
GLX
MIT-SCREEN-SAVER
MIT-SHM
MIT-SUNDRY-NONSTANDARD
RANDR
RECORD
RENDER
SECURITY
SGI-GLX
SHAPE
SYNC
TOG-CUP
X-Resource
XAccessControlExtension
XC-APPGROUP
XC-MISC
XFIXES
XFree86-Bigfont
XFree86-DGA
XFree86-DRI
XFree86-Misc
XFree86-VidModeExtension
XINERAMA
XInputExtension
XKEYBOARD
XTEST
XVideo
default screen number: 0
number of screens: 1

screen #0:
dimensions: 1400x1050 pixels (370x277 millimeters)
resolution: 96x96 dots per inch
depths (7): 24, 1, 4, 8, 15, 16, 32
root window id: 0x59
depth of root window: 24 planes
number of colormaps: minimum 1, maximum 1
default colormap: 0x20
default number of colormap cells: 256
preallocated pixels: black 0, white 16777215
options: backing-store NO, save-unders NO
largest cursor: 64x64
current input event mask: 0xd0001d
KeyPressMask ButtonPressMask ButtonReleaseMask
EnterWindowMask SubstructureRedirectMask PropertyChangeMask
ColormapChangeMask
number of visuals: 17
default visual id: 0x23
visual:
visual id: 0x23
class: TrueColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
...

-----------------------------------

Running xdpyinfo under FreeBSD 6.2/Xorg 7.2 (same hardware and xorg.conf)
gives the following data:

name of display: :0.0
version number: 11.0
vendor string: The X.Org Foundation
vendor release number: 70200000
X.Org version: 7.2.0
maximum request size: 16777212 bytes
motion buffer size: 256
bitmap unit, bit order, padding: 32, LSBFirst, 32
image byte order: LSBFirst
number of supported pixmap formats: 7
supported pixmap formats:
depth 1, bits_per_pixel 1, scanline_pad 32
depth 4, bits_per_pixel 8, scanline_pad 32
depth 8, bits_per_pixel 8, scanline_pad 32
depth 15, bits_per_pixel 16, scanline_pad 32
depth 16, bits_per_pixel 16, scanline_pad 32
depth 24, bits_per_pixel 32, scanline_pad 32
depth 32, bits_per_pixel 32, scanline_pad 32
keycode range: minimum 8, maximum 255
focus: window 0x40000d, revert to PointerRoot
number of extensions: 32
BIG-REQUESTS
DAMAGE
DEC-XTRAP
DOUBLE-BUFFER
DPMS
Extended-Visual-Information
GLX
MIT-SCREEN-SAVER
MIT-SHM
MIT-SUNDRY-NONSTANDARD
RANDR
RECORD
RENDER
SECURITY
SGI-GLX
SHAPE
SYNC
TOG-CUP
X-Resource
XAccessControlExtension
XC-APPGROUP
XC-MISC
XFIXES
XFree86-Bigfont
XFree86-DGA
XFree86-DRI
XFree86-Misc
XFree86-VidModeExtension
XInputExtension
XKEYBOARD
XTEST
XVideo
default screen number: 0
number of screens: 1

screen #0:
print screen: no
dimensions: 1024x768 pixels (347x260 millimeters)
resolution: 75x75 dots per inch
depths (7): 24, 1, 4, 8, 15, 16, 32
root window id: 0x4c
depth of root window: 24 planes
number of colormaps: minimum 1, maximum 1
default colormap: 0x20
default number of colormap cells: 256
preallocated pixels: black 0, white 16777215
options: backing-store NO, save-unders NO
largest cursor: 64x64
current input event mask: 0xd0001d
KeyPressMask ButtonPressMask ButtonReleaseMask
EnterWindowMask SubstructureRedirectMask PropertyChangeMask
ColormapChangeMask
number of visuals: 16
default visual id: 0x23
visual:
visual id: 0x23
class: TrueColor
depth: 24 planes
available colormap entries: 256 per subfield
red, green, blue masks: 0xff0000, 0xff00, 0xff
significant bits in color specification: 8 bits
...

-----------------------------------

Does this give any clues as to what is wrong?

--
Will
.