Well to somebody who doesn't know any better it will be worth more. Those who do won't pay much for it. There was a time when a 3.2 GHz P4 was a rocket, but that was nearly 2 years ago or more. Now that's just a couple steps higher than the slowest Prescot and not so impressive at most things.
If you're going 64 bit to run XP 64 Bit Edition I'd wait until they come out with a decent anti-virus program for it. If you want to go 64 bit because you want better performance for your money it's AMD64 time for you.
Can't give you a price unless you tell us what country you're in.