Port 8000 is not open in Windows Vista except when running as a system administrator. And so with User Account Control (UAC) enabled, you cannot navigate to http://localhost:8000 or run self-hosted WCF Services without opening the port. To open for your user account, open a command prompt (running as Administrator) and invoke the netsh utility:
netsh http add urlacl url=http://+:8000/ user=MYMACHINE\UserName