Which cpu should I buy?

I'm looking to buy a cpu for up to $400, and I came across this:
http://www.newegg.com/Product/Product.aspx?Item=N82E16819116501

I don't know much about computers and was wondering if I should get ivy bridge or sandy bridge, also what makes those two different?

 

[Lilly]

Ivy Bridge is a bit faster, it tested in multicore rendering at 1.65 whereas Sandy Bridge scored 1.58, more energy efficient and has better graphics.

 

[Disparity]

Ivy Bridge all the way, thats like top quality CPU, or atleast whats in stores atm.