Here's a great section on MSDN about choosing a distributed technology
(web services vs WCF vs remoting etc).

The articles also contain performance guidance and tips for web
services.

http://msdn.microsoft.com/webservices/choosing/default.aspx

Josh
http://www.thejoyofcode.com/

Hi Max (again),

With regards your question - performance wise there should be no
difference between 10 WS with 1 method and 1 WS with 10 methods.
However, 10 WS with 1 method could be easily split between servers if
performance becomes an issue (scalability).

However, performance isn't really a consideration when I decide what
methods go into what Web Services. I just group the methods together
where it makes most sense, similar to how I group functionality into
objects with OO. It's all about separation of concerns and reuse. Then,
if I need to scale out, I can load balance any of the services that are
underpeforming.

Josh
http://www.thejoyofcode.com/