Found this in the included readme file:
The full game differs in the following ways compared to this demo:
* Textures in the full game are, on average, 2X higher resolution
than in the demo. The textures in the demo were reduced because
of download size limitations.
* The full game includes over 30 maps, compared to the 4 in the demo.
* The full game includes over 50 characters, versus 4 in the demo.
* The demo only supports "instant action" mode, Internet and LAN play.
The full version also contains the single-player ladder, enabling you
to play through the game while managing a team roster.
* The demo doesn't include the Unreal editor and content-creation tools
which ship with the final game, enabling you to build new levels, modify
existing ones, and create game mods.
* The full version includes 6 mutators offering new variations on
gameplay, versus 2 in the demo.
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The NVIDIA 40.41 drivers are known to have visual flaws and performance
problems (hitching) with the Unreal Tournament 2003 Demo which are not
present in the 30.82 drivers. The issue has been addressed by NVIDIA
and future drivers released by NVIDIA will contain the appropriate fixes.
If you are currently running the 40.41 drivers please either downgrade
to 30.82 or install newer drivers when available.
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Guess you guys complaining on the visual quality where right
I also had problems with my drivers as described, I will now downgrade to the recommended version and try again...