While you may think that the bus speed is a limitation of the motherboard (and in some cases it is) you can't necessarily drop in a new chip and expect it to do the same. Is the new chip a 133mhz chip also? It might be 166mhz. I think maybe the 3000+ (almost certain its 166mhz by default, more overclocking room via the bus) may be the better chip if you are trying to keep the platform and just upgrade the chip as high as it will go. But you can get a athlon II 245 and mobo for 50-60 dollars these days, that will absolutely outperform either of those chips.