IIRC I had the same memory problem with Knoppix 3.3 and i810, and solved it by adding a line for more video memory in /etc/X11/XF86config-4 :
Code:
Section "Device"
        ### Available Driver options are:-
# sw_cursor is needed for some ati and radeon cards
        #Option     "sw_cursor"
        #Option     "hw_cursor"
        #Option     "NoAccel"
        #Option     "ShowCache"
        #Option     "ShadowFB"
        #Option     "UseFBDev"
        #Option     "Rotate"
        Identifier  "Card0"
# The following line is auto-generated by KNOPPIX mkxf86config
        Driver      "i810"
        VendorName  "All"
        BoardName   "All"
#       BusID       "PCI:1:0:0"
        VideoRam    16384
EndSection