Many times in an Extranet scenario I see that Clients are having to enter domainusername in the username box, although this isn't a particular problem if often causes a few user error issues which could be easily avoided.
1. Locate your externally facing website in IIS
2. Choose Properties on this web site
3. Choose the Directory Security tab
4. Choose Edit.. under the Authentication and access control heading
5. In the Default domain box enter the domain that users will use and click OK twice
Done! Your users will no longer have to type domainusername just username instead
jennye