Whole new plan - Need some rec & advice

Just decided i'm going to a local computer store instead of ordering online. One not to far from me, but anyway they have a vareity of stores in the area just in case there isn't a part in stock. Yet they don't have two of my GPU options that I had in mind.

The ATi Radeon HD 4870

& the

Asus ATi Radeon HD 4870x2 <- Was hoping to get this bad boy.

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So it seems like I will be ordering the new Sapphire Vapour-X 5870 HD.Back then I didn't know the wattage rates for certain gc's until Twist recommended me to look at this

http://www.computerforum.com/90110-power-recommendation...

Yet now since im stuck with the 5xxx series card I was wondering what kind of psu i'll need in order to adjust the stability level to excellent.

Here a site of the local store's website

http://www.canadacomputers.com/


BTW, is the 4870 HD GC gaining a better rare level as the days go on or something ? I don't see it in the site at all and this is one of the top store's in Canada.