I tried your suggestion, which I have used in the past to pass
credentials.  In this instance, I'm needing to send the credentials via
the HTTP headers, not part of the soap headers.  According to RFC 2617,
the HTTP header should include "Authorization: Basic uid:password"
format.  Using the trace built into IIS I looked at the incomming
request to the webservice to locate the header information and check if
any credentials that I set was found within the header, but could not
find any.

this is the information in the HTTP header:

Headers Collection
Name Value
Connection Keep-Alive
Content-Length 4068
Content-Type text/xml; charset=utf-8
Expect 100-continue
Host localhost
User-Agent Mozilla/4.0 (compatible; MSIE 6.0; MS Web Services Client
Protocol 2.0.50727.42)
VsDebuggerCausalityData
uIDPowZg+yq+Zv9BnmiKUtX0pxsBAAAANneykaH6Wky4N0BqGyE1RI8QHDH3KGRPmY2NJ9d7/egACAAA

SOAPAction "http://tempuri.org/GetVersion"

-----------------------------------------------------------------

Here's a snippet of what code i used to set the network credentials.

               System.Net.NetworkCredential cred = new
System.Net.NetworkCredential("user", "user");
               System.Net.CredentialCache cache = new
System.Net.CredentialCache();
               cache.Add(new Uri("www.webservice.asmx"), "Basic",
cred);
               webService.Credentials = cache;

Am I going about this the wrong way?

Thanks.