No I think you may be missing the point of my query -- what I want to do, for example, is simply run my DSTV decoder through my computer monitor when and if I want, instead of through the TV. The solution you propose is far too complex (and expensive) for this supposedly simple task.
The alternative is to buy another TV, but as I already have a perfectly good TV and a perfectly good computer monitor this would be a waste. So my query still stands, thanks!
Sounds like you need an AV to VGA adapter then
http://www.hdcabling.co.za/rca-to-v...tandard-av-rca-player-to-pc-screen-p-176.html
http://www.avsupply.co.za/product_info.php/bnc-composite-rca-video-vga-video-converter-p-328
Audio will be a problem unless you plan on using some PC speakers