Potentially interested in veganism - how good are meat substitutes?

I would love to go vegan for ethical reasons but I get the feeling without meat I would just feel very depressed at dinner times (I know that sounds terrible, but I've been conditioned for 26 years on meat).

How good are "fake meats" eg Linda McCartney sausages etc? Which ones are the best (I'd be happy to pay more?) Are there any which genuinely come close to tasting like the real thing?