I saw an ad today for a Samsung 43" rear projection TV for only £599!! This seems unbelievably cheap to me - having only used CRT TVs myself in the past, can anyone vouch for the picture quality on rear projection sets? I'm a keen gamer so am concerned that the picture quality mght not be sharp enough...

Thats the beauty of rear projection and crt sets at the moment because everybody's raging about plasma and lcd, it means prices have dropped dramatically. Quality of rear projection and crt is better than lcd and plasma too, only issue really is size. If you are worried about the sharpness of picture ask for a demo and then judge from that

Depends what type of rear projection TV it is. DLP? LCD? Seeing demos of rear-pro screens I've found the quality can vary greatly...

It doesn't specify, so I'm guessing it's not a DLP projector. (i know they're meant to be the best) I think it might be just a stardard CRT one. Generally speaking, do they not yield as good a picture?

Generally speaking they do not. Also you mention you're a keen gamer and with the next generation of consoles round the corner promising HD compatibility, if you want optimum visuals, you'll need an HDMI port. These are less likely to be found in CRT models so definately check, in particular the cheaper models are even more likely not to have this compatibilty which will likely be a big issue for you.