Xeon 603 and 604 pin are they interchangable??

I own a 603 pin processor and I am looking at a mother board with a 604 pin socket any info?

Xeon 603 and 604 pin are they interchangable??

http://www.tech-faq.com/socket-604.shtml...
economically my experience is that motherboards and cpus that are the same socket arent compatible muchless if they are different sockets. if you own the money to waste if it doesnt work psyche say progress ahead but i wouldnt risk it.