。分辩率过高。。请问怎么解决！！急

[lbpda]

小弟刚开始接触linux，不大懂。现在就遇到一个分辨率的问题。为了实现3D桌面效果，现在搞得分辨率过高了。上网搜了不少资料，还是没能解决。情况如下：
启用X server服务后，分辨率就好高，字小得看不清。想调回1024*768。如果直接用"系统－首选项－屏幕分辨率“调的话，就会出现一个对话框”Xserver不支持XRandR扩展，无法在运行时刻对分辨率进行更改“。后来在屏蔽fglrx核心模块后就恢复到了1024*768了。但好像此时，驱动并没有用上。画面有点卡，更别说用3D桌面了。因为在红旗6.5里面也出现了这样的问题。我的是ATI HD3450显卡。请问这个怎么解决呢？是显卡驱动问题吗？
我的xorg.conf是这样的:# xorg.conf (X.Org X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the xorg.conf manual page.
# (Type "man xorg.conf" at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
# sudo dpkg-reconfigure -phigh xserver-xorg

Section "ServerLayout"
Identifier "Default Layout"
Screen 0 "aticonfig-Screen[0]-0" 0 0
EndSection

Section "Files"
EndSection

Section "Module"
Load "glx"
EndSection

Section "ServerFlags"
Option "AIGLX" "off"
EndSection

Section "InputDevice"
Identifier "Generic Keyboard"
Driver "kbd"
Option "XkbRules" "xorg"
Option "XkbModel" "pc105"
Option "XkbLayout" "us"
EndSection

Section "InputDevice"
Identifier "Configured Mouse"
Driver "mouse"
Option "CorePointer"
EndSection

Section "Monitor"
Identifier "aticonfig-Monitor[0]-0"
Option "VendorName" "ATI Proprietary Driver"
Option "ModelName" "Generic Autodetecting Monitor"
Option "DPMS" "true"
EndSection

Section "Device"
Identifier "aticonfig-Device[0]-0"
Driver "fglrx"
Option "VideoOverlay" "on"
Option "OpenGLOverlay" "off"
BusID "PCI:2:0:0"
EndSection

Section "Screen"
Identifier "aticonfig-Screen[0]-0"
Device "aticonfig-Device[0]-0"
Monitor "aticonfig-Monitor[0]-0"
DefaultDepth 24
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection

Section "Extensions"
Option "Composite" "0"
EndSection

[qiang_liu8183]

新人最好多去Wiki充充电，这些问题在Wiki都有解决方法，对你会有很大帮助