Problem:

# hwinfo --monitor
31: None 00.0: 10000 Monitor
  [Created at monitor.93]
  Unique ID: rdCR.OYGIo1r6D00
  Hardware Class: monitor
  Model: "SAMSUNG SyncMaster"
  Vendor: SAM "SAMSUNG"
  Device: eisa 0x027e "SyncMaster"
  Serial ID: "HS3P516457"
  Resolution: 720x400@70Hz
  Resolution: 640x480@60Hz
  Resolution: 640x480@67Hz
  Resolution: 640x480@72Hz
  Resolution: 640x480@75Hz
  Resolution: 800x600@56Hz
  Resolution: 800x600@60Hz
  Resolution: 800x600@72Hz
  Resolution: 800x600@75Hz
  Resolution: 832x624@75Hz
  Resolution: 1024x768@60Hz
  Resolution: 1024x768@70Hz
  Resolution: 1024x768@75Hz
  Resolution: 1280x1024@75Hz
  Resolution: 1280x1024@60Hz
  Resolution: 1280x960@60Hz
  Resolution: 1152x864@75Hz
  Resolution: 1680x1050@60Hz
  Size: 474x296 mm
  Detailed Timings:
     Resolution: 1680x1050
     Horizontal: 1680 1728 1760 1840 (+48 +80 +160) -hsync
       Vertical: 1050 1053 1059 1080 (+3 +9 +30) +vsync
    Frequencies: 119.00 MHz, 64.67 kHz, 59.88 Hz
  Driver Info #0:
    Max. Resolution: 1680x1050
    Vert. Sync Range: 56-75 Hz
    Hor. Sync Range: 30-81 kHz
    Bandwidth: 119 MHz
  Config Status: cfg=new, avail=yes, need=no, active=unknown
root@meilenschwein ~ #

mika@meilenschwein ~ % hwinfo --monitor
29: None 00.0: 10000 Monitor
  [Created at fb.71]
  Unique ID: rdCR.EY_qmtb9YY0
  Hardware Class: monitor
  Model: "Generic Monitor"
  Vendor: "Generic"
  Device: "Monitor"
  Resolution: 1280x1024@77Hz
  Driver Info #0:
    Max. Resolution: 1280x1024
    Vert. Sync Range: 50-90 Hz
    Hor. Sync Range: 31-82 kHz
  Config Status: cfg=new, avail=yes, need=no, active=unknown
mika@meilenschwein ~ %

Wheras the information from user root is correct for the *external* monitor, 
the information you retrieve when running as normal user is just wrong. I 
didn't find a way to get information of *both* monitors without running 'hwinfo 
--all' which sucks because several systems have problems (like kernel crash) 
when running that....