Changing seta image_cacheMegs "something" doesn't make any difference to my timedemo1 scores (always 5.0 )

I optimistically tried changing seta image_useCache "0" to "1" but when I do that the game doesn't load and I get reverted back to the windows desktop.

Has anyone else had any better luck, oh, and BTW, I'm using a PC with 1GB, P4 2.5GHz, 64MB Nvidia gfx card?