Why is this card so cheap and other questions?

Hey i've got a few questions, firstly im looking into buying a new graphics card! Dont worry there's hopefully no stupid questions here. First if you could look at this card

http://www.overclockers.co.uk/acat [...] eries.html

(the one im talking about is the powercolor X850XT at £199.69)

My main question about this card is, why is it so cheap, even compared to the sapphire X800XL on the same page? I know the X850XT is a great card, however is powercolor notoriously cheap and/or bad?

Also my other question relates to another card

http://www.overclockers.co.uk/acat [...] eries.html

(the one i'm talking about is the BFG card at the top of the page)

Would this be a wiser purchase due to it's Shader model 3 support or do it's slower speeds hinder it too much? To put it another way are the 6800GS cards too slow and therfore cant take advantage of the SM3 supprt and therefore can't compete with the X850XT?

Well the same card by sapphire can set you back anywhere between 290 and 340 pounds!

Powercolors are decent cards, they might not have the best quality RAM and such but if you leave them at their stock clocks they're fine.

If you're an overclocker, it's sometimes better to get a brand that uses higher-quality chips than is needed, to give you some overclocking headroom.