I have the PowerColor Radeon HD4850 PCS+ 512MB. It's a good little card, but I'm beginning to want more. My dilemma is this. Do I get another HD4850 512MB because they're so affordable right now and put it in crossfire, or do I sell my card (probably only for £70) and buy something else? Perhaps an HD4850 1GB or HD4870 1GB? I haven't got a lot of money available right now, so I'd want something really good value.