HTTP GET/POST are disabled by default on web servers in the new .NET 1.1 which could make creating REST-type web services more difficult. The error message you get is:
Request format is unrecognized.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
The fix is to enable GET/POST. See http://support.microsoft.com/default.aspx?scid=kb;en-us;819267 to enable it.