I have (and LOVE) the Belkin AV55000.

http://www.soundandvisionmag.com/audioaccessories/1072/belkin-pure-av-remotetv-av55000.html

I don't believe they make it any more, but I think you can still find em around. They are pricey, but work exactly as advertised. No HD, only SD.

I use it to send video/audio from my HR20 to a screen in my bedroom, but you can plug anything into it (ie: your friend's laptop).

I previously used a Terk Leapfrog video/audio sender (2.4GHz) with very mixed results (lot's of interference).

The other thing you might want to keep an eye on (it's not out yet) is the http://www.engadget.com/2007/01/07/sling-medias-new-slingcatcher/ It needs a Slingbox on the transmitting side, so maybe it's a more expensive solution than what you want...

- Jon