There are a couple of things you can do to see if you've got vlc set up correctly.

1) On your PC. open a browser and go to http://127.0.0.1:8080 and you should see a simple media player interface. If not you won't be able to connect remotely.

2) if 1) worked. Open the browser on your n900 and got to http://YOUR.PC.IP.ADDRESS:8080 where you should see the same thing.

If 1) fails - vlc needs to have the http interface turned on.

if 2) fails - vlc needs to allow your IP address or you may have a firewall issue.

What OS and version of VLC do you use?