Computer audio and external speakers

["Renato" <re.luppi@xxxxxxxxx>]

I'd like to connect my computer to external speakers, so I can enjoy
MP3s in some other rooms in the house. My house is wired for audio,
which means I have ceiling speakers with volume control or audio
outlets (for banana plugs) on the walls available in some rooms.

Speakers require two wires (usually black and red ?), but I noticed the
audio output from my computer is composed by just one single outlet,
which uses 1/8'' plugs. I also noticed that both the left and right
computer speakers that I have connected to my computer today are
sharing the same audio output. My computer's manual says that I can
configure it to provide 5.1 audio, and I understood it would use
traditional inputs like microphone as audio outputs (?). The idea is to
keep the computer speakers that I have in place today and use one of
such configured audio outputs to connect to the house audio outlets,
and then plug additional speakers in other rooms.

Questions:
1- Do I need to connect the elected computer audio output into an
amplifier or could I feed the house audio wiring directly from the
computer?
2- Has anybody tried this 5.1 configuration?

Silly question:
Where is the second wire? Today, both left and right computer speakers
are sharing the same audio cable, which is plugged in only one audio
output in the back of the computer. Is this cable composed by two
wires?

Thank you.