Newer 3d chips and older cpu's

I read this forum several months ago and from what i read, I decided that I might take advantage of the Tualatin benefits when the prices came down. I built my computer around a new asus tuv4x motherboard with support for tualatin 1.2ghz+ and all was well. I managed to get a cheap pentium 3 733e as a starter chip ($50 cdn) which makes me all around pleases with my my machine.
Then i got a radeon 8500 oem from a guy across canada. Mainly, the issues I am experiencing are probably attributed to that alone, but I will need imput.

I know 3dmark is not a tramendously important benchmark and not grossly accurate. However, I ran it and was dismayed by the display results i got. My 3dmarks werent that bad, 5314, but I was quite dissappointed by the chop that the card spat at me through tests that should have had no chop at all. on car chase high detail, the card literally chokes and spits out a low of 12 fps. I dont know whether to trust these numbers but the frame rate was incredibly choppy. next test, dragothic, no chop. none at all. all tests run withing chop. 3rd test, lobby, low detail runs incredibly fast where hgih detail stops to cache itself at multiple points.
Nature runs at 12 fps and chops a LOT.

as for all the other tests, I have no complaints but the point sprites run really laggy.

Mainly, I am experiencing some nasty video speed and i was wondering if anyone would happen to know of a setting that i might have overlooked in my bios. I have not over clocked the system except on one occasion to do a video encode so there is nothing wrong with it.
I am sort of lost. Is this the result im supposed to get from such a "slow" processor?

Oh and forgive me, this is my first post on the boards. I send a general greeting to everyone.