"ANTS (Advanced .NET Testing System) is a load testing tool by Red Gate Software which allows web services to be tested using SOAP. An evaluation copy of ANTS Load can be downloaded from Red Gate's website."http://www.red-gate.com/
Does anybody know of any similar tool that is free that can load test web services?
Try Visual Studio Team System or Visual Studio Team Tester Edition.
Create a Web Service Test: http://msdn2.microsoft.com/en-us/library/ms182557(VS.80).aspx
Load Testing Web Services with Unit Tests: http://blogs.msdn.com/slumley/pages/load-testing-web-services-with-unit-tests.aspx