Grace à vos conseils, j'ai maintenant une interface graphique. Merci.
J'ai dû bidouiller xorg.com pour y placer les bonnes valeurs. Je vous livre ici le résultat (pour les possesseur d'un écran identique au mien).
# Xorg configuration created by pyxf86config
Section "ServerLayout"
Identifier "Default Layout"
Screen 0 "Screen1" 0 0
InputDevice "Keyboard0" "CoreKeyboard"
EndSection
Section "InputDevice"
Identifier "Keyboard0"
Driver "kbd"
Option "XkbModel" "pc105"
Option "XkbLayout" "be"
EndSection
Section "Monitor"
Identifier "monitor1"
VendorName "Generic"
ModelName "1280x1024 @ 76 Hz"
HorizSync 31.5-82
VertRefresh 50-90
# TV fullscreen mode or DVD fullscreen output.
# 768x576 @ 79 Hz, 50 kHz hsync
ModeLine "768x576" 50.00 768 832 846 1000 576 590 595 630
# 768x576 @ 100 Hz, 61.6 kHz hsync
ModeLine "768x576" 63.07 768 800 960 1024 576 578 590 616
EndSection
Section "Device"
Identifier "Videocard0"
Driver "vesa"
EndSection
Section "Screen"
Identifier "screen1"
Device "Videocard0"
Monitor "monitor1"
DefaultColorDepth 24
Subsection "Display"
Depth 8
Modes "1280x1024" "1024x768" "832x624" "800x600" "640x480" "480x360" "320x240"
EndSubsection
Subsection "Display"
Depth 15
Modes "1280x1024" "1024x768" "832x624" "800x600" "640x480" "480x360" "320x240"
EndSubsection
Subsection "Display"
Depth 16
Modes "1280x1024" "1024x768" "832x624" "800x600" "640x480" "480x360" "320x240"
EndSubsection
Subsection "Display"
Depth 24
Modes "1280x1024" "1024x768" "832x624" "800x600" "640x480" "480x360" "320x240"
EndSubsection
EndSection