Depends how much you're willing to spend.
The 6200 is a bit on the low end. Id try and either go for a 6600 (the hundreds number is indicitive of how "good" it is, within the thousands series - IE the 6 series).
www.overclockers.co.uk is a very reliable and relatively cheap site. They usually always have offers on. ATI do some fantastic cards... their very latest don't really live up to NVidia's latest, but you probably won't be forking out the amount they go for.
Example,
http://www.overclockers.co.uk/showpr...=56&subcat=356
Although this is under £30, I don't know if it would work with either
http://www.overclockers.co.uk/showpr...=56&subcat=416
£100,
http://www.overclockers.co.uk/showpr...=56&subcat=404. I paid £180 for something similar about 6 months ago. If you really care about KR, go for a card now, but if you don't want to adopt yet it may be worth waiting till you really want to play, as cards will go down in price all the time.