I run dual gtx 550 ti's and even with runining 1 card i run skyrim max settings no lag, Payed 220.00 for 1 card a year ago and the 2nd one i bought around xmas was 150.00.
If your mother board is set up for Sli it is worth it , than wait a year buy the 2nd card for about 150.00
But your processor and ram will be another big factor, G-card can only do so much.
But they are a decent card for the price. I got a 10 year waranty on mine !!!