I've used GoToMyPC for many years and swear by it. Excellent piece of software.
Works from absolutely anywhere - even heavily fortified corporate machines that don't let you download stuff without the IT departments permission.
Remote printing, audio, video - 100% functionality.
Costs me US$19 a month for one nominated machine.
I used to run our entire home network (five machines) through it - but it got expensive. Now I use RealVNC to look at any of the home network *via* the network from my desktop machine - and still have the GTMP service for that....so I can log into my desktop with GTMP and then look at any machine on the network via RealVNC.
RealVNC was free of charge for all WindowsXP work, but chargeable for Vista. US$30, rings a bell.
The RealVNC required that the computer being looked AT had to have a handshake pre configured FROM the machine that was lookintg at it.....so I'm assuming I couldn't just grab a computer terminal somewhere and connect via RealVNC from outside.
RealVNC doesn't carry audio or video between machines.