A2002 VOL1 on PIV GF4

HI there,Anyone could explaine to me why on 2 computers with the same FS2002 (exactly the same), one is AMD Athlon1.4 512SDRAM Geforce3 Ti500, and the other PIV2.4Ghz DDR512 Geforce4 Ti460, both win Win XP and the same Nvidia drivers, the Wilco A2002 airports runs much better (fps I mean) on the older AMD machine that on new one.And the more strange is that every of the other sceneries freeware or payware runs faster (almost 50%) than the AMD computer.I really don't know whats wrong, since i was surprise with the complexity of the sceneries and didn't hurt the fps on the AMD machine!Cheers,Miguel