Regarding the video driver, you can specify the max video ram in
/etc/X11/xorg.conf

xorg.conf
-------------
Section "Device"
Identifier "Intel Corp.|82865G Integrated Graphics D"
Driver "i810"
BoardName "Unknown"
VideoRam 32768
Option "XvMCSurfaces" "6"
EndSection
------------------------

BTW for DRI to work, min of 32M videoRam is required. Do check with
$glxinfo
that DRI is enabled.