Getting Silverlight web part to deploy in SharePoint

I'm trying to get a Silverlight Web Part working in MOSS by creating it in Visual Studio 2008 (based on the tutorial here: http://msdn.microsoft.com/en-us/magazine/dd148643.aspx).

When I try to deploy it, I get the error message:
The HTTP request is unauthorized with client authentication scheme 'Negotiate'. The authentication header received from the server was 'NTLM'.

I've changed the authentication settings for the SharePoint site to "Negotiate,NTLM" as this article suggests: http://support.microsoft.com/kb/215383

When I enable anonymous access on the VSeWSS website in IIS, I stop getting that error message and instead get this one:
The requested service, 'http://[IP address]/SPService.svc' could not be activated. See the server's diagnostic trace logs for more information.

Going to the Event Log reveals this error for the System.ServiceModel 3.0 source:
The exception message is: Security settings for this service require Windows Authentication but it is not enabled for the IIS application that hosts this service.

All of the documentation for this error seems to indicate that I need to DISable the anonymous access.  All of my websites in IIS have Integrated Windows authentication enabled.

Any help?

Thanks!