Honestly, I'm not sure if the 460 will be of any benefit to you bro. If your limited to $150 or less, wait till the next generation come out. The cards in that price range will likely be twice as fast as your 260GTX, give or take a little.
When I had my 5770, it was every bit as fast as my old GTX260 Core216... infact it felt a bit faster. I'd probably put my 5770 closer to the GTX275... maybe a tad below it. The 460 is a bit fater than the 5770 so...
Yes a 460 would be faster than your 260. Noticeably? Not very often I'd imagine. I'd hold out till next gen. It's likely less than 4 months away.