I did a research for a while, and I just needed some upgrade from my celeron 450mhz
so got the EPOX 8KTA3 motherboard with a Athlon Thunderbird 900mhz Chip.
you can get them both for $249 + shipping at mwave.com
I think even a thunderbird 700mhz should do you perfectly fine.
Just a suggestion, I don't know what you need it for or anything.
But I don't think it's necessary to buy those gigahertz cpus, I think
the 900mhz wasn't necessary either.. ok, I'm just babbling.