Upgrading from 9800gtx/PSU?

[MetaKnight]

First here's my specs:
Q6600 Oc'd to 2.9Ghz
4GB GSkill 800mhz (ram)
Asus P5n-d mobo
RAIDMAX HYBRID 2 RX-730SS 730W
9800gtx OC PnY

My range is about 250$ if I sell this card it will be 300ish.

I'm going to sell my 9800gtx on Craigslist for about 50-60 dollars (found a buyer I think). I've been dong some research and I found these to be the best buy for my dollar:

http://www.newegg.com/Product/Product.aspx?Item=N82E16814130699
570gtx refurb 250$

http://www.newegg.com/Product/Product.aspx?Item=N82E16814130759
480gtx new 210$

Which leads me to my next question, which one will I need a new PSU for? And is there an Radeon alternative that allows me to get the same performance as these two with my PS right now. I really don't know much about the AMD cards..

Thanks! :]

 

[MetaKnight]

Best answer selected by MetaKnight.