Can't Publish to Local IIS Server

I hope someone can help me with this problem....

I installed IIS from my XP Pro CD, along with the FrontPage Server
Extensions. I have a web already published to c:\inetpub\wwwroot (from a
prior installation) and can view it in my browser at http://localhost.

However, when I try to republish the same web to http://localhost in
FrontPage 2000, a dialog box pops up saying, "This operation requires
author permission for localhost:80". I've tried my own login and password,
as well as Administrator, and neither works. Can anyone tell me, first of
all, why I'm being prompted, and second, what login and password it's
looking for?

The IIS snapin sayis that Default Web Site is running. How can I check to
make sure that the server extensions are installed and working properly?

I seem to remember that I had this problem after I installed IIS the first
time, but unfortunately, I don't remember what I did to resolve it.

Thanks.

--
Keith