Question: 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?

Answer: 
try:

<http://localhost:8080/Services/V1.0/ServerStatus.asmx>. This will tell you if TFS is up and running. If you are getting anything else you need to look into IIS issues.
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.