If you don't have a WiFi card, you can purchase an inexpensive one like linksys. These cards are very well supported.
Look through your packages using "synaptic package manger" and search for ffmeg or ffmpg(it begins with ffm...lol) and install all packages with that name. Let us know what happened.
You don't uninstal linux, the HD will have to be reformated or the OS overwritten with another OS.
From what I know, ubuntu server and debian are best for servers. Debian is gui based by defualt and ubuntu server uses a shell prompt. Use debian, it is as easy as ubuntu and lightweight. Its also very extensible so you can customize it. Any linux Os will perform the above task. In my experience, ubuntu and Debian have been the easiest to use.
Are you saying when you log into your desktop, the fan stops?