Help! Can't get Web Services to display in browser - tries to open in Visual Studio

Question

Everywhere I've read and tried examples... the samples have me test the web services by typing the web service URL in the browser. Example: http://localhost/ProductService.asmx However, my browser always tries to open the .asmx in Visual Studio. What do I need to modify in order to make this work. I am currently running Windows 2000 with IIS 5.0. Thanks Carrie