It is true that Intel has an advantage on AMD in the Multi-processor systems. But for the price of a multi-processor intel setup, you could build 2 AMD servers, and divide the networking tasks between them, or subnet them.
Anyway, a multiprocessed system is really needed for an application server, and is only slightly helpful for every other type of server with less than 50 workstations.
Forget about seeing any use in the second processor for Win98 or ME. So, if you have an application server, and you can't subnet your network with a backup domain controller, get the Intel. Otherwise, go with AMD for price and performance.