What kind of tv do you have. Computer screens have a much higher resolution than a standard tv, trying to do normal computer work, email, browsing etc will make you go blind straining to see what's going on, you'll probably have to drop the resolution on the pc but then websites will half disappear off the screen.
The other problem is with wireless keyboard and mouse, they usually work on line of sight, it will be difficult to get this working through walls and floors.
If you are intending to watch movies stored on your hard drive then that makes more sense. Best option here is to get an external hard disk drive with a built in media player which you hook up to your tv like a DVD player.
The only other way is to get a laptop with tv out. You can wirelessly access files on your main pc, and can hook the lappy to the telly for watching movies. I can watch divx films on my tv which stream effortlessly to my laptop from bedroom comp. High definition films will struggle though as they will need lots of wireless 'headroom'.
