Non so se puoi portare la risoluzione fino a 1280x1024@24 di profondità... dalla configurazione non sembra supportarlo... cmq puoi modificare cosi':

codice:
Section "Screen"
    Identifier  "Screen 1"
    Device      "GeForce"
    Monitor     "Philips"
    DefaultDepth 24
                                                                                
    Subsection "Display"
        Depth       8
        Modes       "1280x1024" "1024x768" "800x600" "640x480"
        ViewPort    0 0
    EndSubsection
    Subsection "Display"
        Depth       16
        Modes       "1280x1024" "1024x768" "800x600" "640x480"
        ViewPort    0 0
    EndSubsection
    Subsection "Display"
        Depth       24
        Modes       "1280x1024" "1152x864"
        ViewPort    0 0
    EndSubsection
EndSection
oppure, se non ti funziona:

codice:
Section "Screen"
    Identifier  "Screen 1"
    Device      "GeForce"
    Monitor     "Philips"
    DefaultDepth 16
                                                                                
    Subsection "Display"
        Depth       8
        Modes       "1280x1024" "1024x768" "800x600" "640x480"
        ViewPort    0 0
    EndSubsection
    Subsection "Display"
        Depth       16
        Modes       "1280x1024" "1024x768" "800x600" "640x480"
        ViewPort    0 0
    EndSubsection
    Subsection "Display"
        Depth       24
        Modes       "1152x864"
        ViewPort    0 0
    EndSubsection
EndSection