It probably does have a pretty good price/performance ratio.

The reason for this being, as you pointed out, that it uses the out of date socket423, rather than the current socket478, so you are buying an 'end of line' P4, which is why it is relatively cheap.

In essence, this means that you will not be able to upgrade it in the future, as all new P4 chips use socket478. Socket423 P4's also run with a FSB (front side bus) of 400MHz, as opposed to socket 478 P4's which can currently run with a FSB of 400, 533, or 800Mhz.

IMHO you would probably be better off getting a mobo that supports socket478 and a FSB of up to 800Mhz, with say a 2.4 Ghz socket478 P4 (400 Mhz FSB) - or faster if your pocket will stretch to that - there is a wide variety of P4s to choose from. In the future you could then upgrade to a faster P4 (800 Mhz FSB) when the prices come down to a more reasonable level without major hassle.