Andy wrote:
I am in the UK.

I would like to take a stereo signal from the line-out of my stereo
(or TV) to the line-in of my PC.

The equipment is in different rooms and the audio cable would be 10
metres. It will be this type:
http://www.maplin.co.uk/images/full/130i0.jpg

I don't understand the technical side but is 10 metres so long that
it might cause audio problems with things like frequency response or
voltage/current levels and so on?

Will I need to get some higher specification audio cable to cover
that distance? I want to keep cost down.

I have used similar cable for a similar purpose over longer distances
with no problems, for general purpose "listening" quality. Buying a
higher spec cable is only going to give a very marginal improvement - if
you really are interested in quality, you would link digital ports using
an optical cable and not use analogue, anyway.

--
Sue