I am currently running my LCD TV as a second monitor in the same room as my PC, watching movies, browsing the web with etc no problems at all. However, I am moving house and the TV will now be downstairs.

Holes have been drilled in the office floor to allow extended Audio, VGA and USB cables to run through to the TV and home theatre system in living room (all fine structurally).

The distance for the cables will be about 5m ish. The intention with the USB cable is to have a 2/4 port usb hub that I can connect dongles to, for my wireless keyboard and mouse, and infrared remote control for the PC.

Rather than using media center, I felt that by having the LCD TV as a 2nd monitor I could always change its designation to the primary display as needed from downstairs which would give me full access to my pc from the living room.

What do you think? I was also wonderring whether any of this could be achieved wirelessly?

Just check the specs on USB cable lengths to be sure you are alright (5 meters max at full speed USB). I have found some devices are picky on the quality of the cable when extended but behave ok with the well shielded USB cables (stiff ones with braid).

http://www.usb.org/about/faq/ans5

Also, need a good quality VGA cable to run that distance or get a VGA extender. This site indicates up to 15 meters with a good quality cable. http://www.ivojo.co.uk/faq.htm

Go DVI or DVI-HDMI and get a HDCP compliant graphics card, or put a different PC downstairs and use a NAS, thats what I would do.