<p>I've installed TFS 2008, but I can't seem to access the server. When I try to connect to it in Visual Studio, I can't. If I try by browser on a remote PC, I get a generic page cannot be displayed. On the server, I get a 403. Nothing was touched in IIS and the service is running as a Network Service. Any ideas?</p>

What happens if you send a simple HTTP request to the server directly?
ie:
telnet  8080 [enter]
GET / HTTP/1.1[enter]
[enter]
[enter]
That might give a hint about whether IIS is actually serving anything.  If you can do that on the server, what about from a different machine?  If the results are different a good guess is there are some security/firewall issues somewhere.  HTH a little.