There should not be a "use ASMX instead of SOAP". ASMX uses SOAP as it's transport mechanism. WCF is Microsoft's latest technology that replaces ASMX, MSMQ, COM+, and .NET remoting into a single technology with a single API. Microsoft's tests have shown it is up to 40% faster than ASMX and remoting. Compared to those two technologies, it is easier to code and configure. It is also SOA-based. WCF in .Net 3.5 can also be either SOAP or REST based.

>Just a few months ago people said ASMX over SOAP. Now WTF over ASMX? Why?