The Intel Pentium III-450 is the "slowest" of the new Pentium III line of Intel Processors. Currently Pentium IIIs come in 450Mhz and 500Mhz ratings with a 550Mhz coming next month. There is really no difference between the 450 and 500 other than multiplier settings and price. Both units look the same and uses the same 4ns cache ram.