@wigsgiw 5830 is 8$ cheaper than 5850 - 280$ 
Woah! Decision made. In terms of the two cards - you could always run two power supplies, meaning you have the option of getting a cheaper / lower wattage power supply to run the 5770 maybe, and then use your 525W for the 5850... perhaps.
yeah, that is just crazy, here in the states a 5830 is about $110 (a sale just ended on a Sapphire 5830 for $90) while a 5850 is around $160...