Are you using Windows Authentication?
If not, it's not your user who needs access, its the user that the web process runs as, on XP this is typically the aspnet_machine name user I think or maybe it's just aspnet I can't remember. In any case its the user configured as the identity on the application pool.
You should configure IIS under the directory security tab for anonymous and windows, and mojoportal by default will use forms authentication not windows auth.
Hope it helps,