Its because 3dmark05 is more GPU dependent.
Thats why a few people including myself dont like synthetic benchmarks..... they dont tell you much, and i think this proves it.... your scored higher in aquamark, and lower in 3dmark.
and Doom3 is the only game i know of with a built in Timedemo, so the Demo score is universal... and it shows real ingame performance for Nvidia cards, that would probably give you a real indication of game performance.