Actually if you want the most bang for your buck (ie Overclocking), skip the Celeron 450-500's, since its at the end of its product life, and you can't squeeze much more out of it than its rated speed.
Right now the hot overclocking processor/motherboard is the new coppermine chips. The PIII-550E Coppermine processor, paired with a Tyan Trinity 400 motherboard. Basically it is like the early Celeron's, in that it is a capable processor as fast as the highest PIII's out there, marketed down (ie marketing gimmic) to a 100Mhz FSB.
Basically, put it in the new VIA 133A chipset motherboards at 133Mhz FSB, and
VIOLA!! you now have a PIII running at
825 Mhz, with the stock cooling fan.
Pair that with a Guillemont 3D Prophet SDR Ge-Force Video Card at $167 off of
http://www.pricewatch.com and you have a system that will compete with the best, but still be economical.
PIII-550E is $260-270
Tyan Trinity 400 Motherboard is $82
Guillemont 3D Prophet SDR Gforce is $167
Total Upgrade Cost of $510 plus shipping and handling, and you will have a machine running in the 800Mhz range, with a G-Force Video card.
IMO this is the peak of the price/performance ratio, and I am currently looking to purchase this myself.
The Celeron stuff at around 500Mhz, is just a minimal upgrade. If you go this route, you will be looking to upgrade again in about a year.
------------------
Vermillion
**MOL**, Men of Leisure,
"Real Men fly Radials, Nancy Boys fly Spitfires"