The Athlon would be faster because it is running a 133MHz fsb vs. the Celeron Tualatin at 100MHz. If you overclock a slower Celeron to a 133MHz fsb or higher, than an equally clocked Athlon on the same fsb speed would be very close with SDRAM. The Celeron does fall way behind though when you pair the Athlon with DDR ram which the Celeron Tualatin can't do. Since the K7S5A can support DDR also, go with the Athlon and upgrade your memory later. If you haven't bought anything yet, get a 1700+ t-bred "B" and a refurbished Nforce2 from newegg. The board and the cpu would be close to the same price, get the cheapest DDR you can find for now to save money. Even at 266MHz DDR this combo will blow away the other options, not even factoring in that the 1700+ will hit 2000-2300MHz. You can upgrade your DDR later.