Hi there,
Had exactly the same problem a few weeks back. The safest way of doing this right is to,
1) uninstall the client and remove the folders left in program files and dokument settings.
2) update the server with the latests patches
3) install the client again. If it gives the same problems use regedit and look for "media server". If its blank, you have to fill in the server name.
4) ON THE FIRST LAUNCH! Use a LAN cable, and not wireless. I had big problems with this untill I used the LAN cable the first time. Afterwards it works over wireless without problems.
And that solved my problems, although I cant guarantee it will do the same for you, but atleast its a start :)
Michel J