Widescreen problem [Allready searched forum]

Hi!
I got a new Acer - Aspire 5000 Laptop! I has SIS M760GX Video adapter. Everything looks really strange! The default resolution is 1024x800. I'm trying to get 1280x800! I'm running Slackware 10.2. Here is my xorg.conf:

Section "Modes"
    Identifier "16:10"
    Modeline "1280x800_60.00"  83.46  1280 1344 1480 1680  800 801 804 828  -HSync +Vsync
EndSection

Section "Monitor"
    Identifier  "My Monitor"
    HorizSync   31.5 - 50.0

    Modeline "1280x800_60.00"  83.46  1280 1344 1480 1680  800 801 804 828  -HSync +Vsync
    VertRefresh 40-90
    UseModes "16:10"
EndSection

Section "Screen"
    Identifier  "Screen 1"
    Device      "VESA Framebuffer"
    Monitor     "My Monitor"

#   DefaultDepth 8
#   DefaultDepth 16
    DefaultDepth 24
#   DefaultDepth 32

    Subsection "Display"
        Depth       8
        Modes "1280x800"
    EndSubsection
    Subsection "Display"
        Depth       16
        Modes "1280x800"
    EndSubsection
    Subsection "Display"
        Depth       24
        Modes "1280x800"
    EndSubsection
    Subsection "Display"
        Depth       32
        Modes "1280x800"
    EndSubsection

EndSection

I used gtf 1280 800 60 to get Modeline. I tryd to change resolution in KDE, but it only provides strandart resolutions. Also I used ctrl alt [+/-] to change resolution, but nothing is happening.. I really hope I wont need any modules. Any suggestions? Thank you!

Wow!!! This is your lucky day...............

I have the same laptop, the portion of my xorg.conf file that matters;

Section "Monitor"
	Identifier   "Monitor0"
	VendorName   "Monitor Vendor"
	ModelName    "LCD Panel 1280x800"
	HorizSync    31.5 - 90.0
	VertRefresh  60.0 - 60.0
	Option	    "dpms"
EndSection

Section "Device"
	Identifier  "Videocard0"
	Driver      "sis"
	VendorName  "Videocard vendor"
	BoardName   "SiS 660/661FX/M661FX/M661MX/741/741GX/M741/760/M760"
EndSection

Section "Screen"
	Identifier "Screen0"
	Device     "Videocard0"
	Monitor    "Monitor0"
	DefaultDepth     24
	SubSection "Display"
		Viewport   0 0
		Depth     16
		Modes    "1280x800" "1024x768" "800x600" "640x480"
	EndSubSection
	SubSection "Display"
		Viewport   0 0
		Depth     24
		Modes    "1280x800" "1024x768" "800x600" "640x480"
	EndSubSection
EndSection

xorgsetup should get it right first time..? Did on my widescreen laptop.

Thank you both very much! Everything is working now!!!