ANY change will toss the results into question.
There could be other factors such as outdated motherboard/other drivers.
I just upgraded my graphics card from an old NVidia GeForce4 Ti 4400 128MB, to an ATI Radeon 9550 256 MB, and I'm totally confused (system is an Athlon XP 2100+ with a Gig of RAM by the way). I was running some framerate tests on Counterstrike Source, and they are shockingly MUCH lower with the new card. On one test, the old framerate was 61.42, and with the new card 37.55. In another test with slightly higher settings, the old card 53.51 and the new card 29.93! Now I know the 9550 isn't a monster of a card, but it should still be faster than that old GeForce4 (probably a 4 year old card). At the VERY LEAST it shouldn't be drastically slower. Any answers/opinions/suggestions?!?!?!?