The cheap way, would be a USB capture device from ebay, and a SCART to AV (red, white, yellow plugs) adapter from a pound shop.
So far, not seen any capture solutions that would handle RGB SCART, so you lose a little quality by using composite video (the usual PAL color ripples etc.). Still better than RF through a tuner, of course
There is an RGB capable system, but when you see the price
http://www.pluggedin.tv/store/SweetS...Processor.html