I can't see any way this is possible. But, as others have said - why USB when there's a myriad of other connection types that are specifically designed to get video from a PC/laptop to an external screen?
Multiple connections for enhanced entertainment -
The USB port allows users to watch videos and pictures on the TV screen using a USB stick or an external HDD. They can also listen to music via its stereo speakers with Dolby® Digital Plus. The integrated USB Video Recording* function means the user can access an external HDD to record favourite TV shows while the three HDMI ports easily connect devices, such as game consoles or Blu-ray™ players, to the RL933 to provide enjoyment of video games and movies in high picture quality on the big screen.
Thanks again, Chronus and Nontek (although you sound pretty 'tech' to me!)
Chronus, I think he's trying to get a slideshow ready for a big family party at the weekend - no time for any upgrades!
Nontek - to my uneducated brain it seems that, if you can watch videos and pictures on the TV from a USB stick, wouldn't that suggest that you should also be able to watch them from your computer's hard drive via USB? Or am I missing something?