The PIII Coppermine always favored D3D benchmarks such as 3DM2k over the Athlon, the Tualatin uses even better cache and more of it. I think it has to do with the superb implementation of SSE. But anyway, the 1.26GHz Tualatin edged out the T-Bird with wins in mostly non memory bandwidth intensive programs, with the T-Bird winning the more bandwidth intensive stuff. Overall it looked like the 1.26GHz Tualatin was a little better that the T-Bird, and much of that could probably be credited to it's cache, since the 256k Tualatin lost to the same T-Bird by similar margins.
The BIGGEST advantage to the T-Bird was that you could get one at higher frequencies for less money. And all the XP's leave the Tualatin in the dust, being clocked higher and having improved architecture.
The higher the frequency, the more important AMD's DDR architecture becomes, so I wouln't be surprized to see the XP1600+ beat a Tualatin Celeron at 1600MHz, even though the XP1600+ only runs at 1400MHz.
What's the frequency, Kenneth?