newbie question - how to get cat5 cabling into walls?

[gyr3]

Hi Folks.

Sorry for jumping in with a total newbie question. I've just stumbled over
KAT5
and it looks like it is ideal for getting my sky digital s-video signal
from the
sky digibox to my PC upstairs.

The problem is... I've not got a clue how to get the cabling from the
downstairs
lounge to the upstairs office. The lounge and office are on diametrically
opposite sides of the house, just for fun :(

I live in a 4 year old house, which isn't wired for cat5.

Could you wise folks throw me a few fairly non-disruptive (and not too
expensive
options on how to run that cat5 cable from the lounge to the office.

Many many thanks.

-- gyre --