Wat PSU should i get?

Corsair 550
http://www.newegg.com/Product/Produc...emory%2c%20Inc.
69.99 after mail in rebate

or
650 watt
http://www.newegg.com/Product/Produc...emory%2c%20Inc.
69.99 mail in rebate

Seconded to the 650tx especially you have a quad cpu. 4870 is a 150w GPU.

Always go with the a quality power supply when powering something you sank a lot of money into. I would recommend, Corsair, Antec, Seasonic, PC Power & cooling. They all make quality products that can be trusted. It all depends on the hardware you are running and the money you want to spend, but remember the power supply is the backbone of your computer.

Corsair HX 620 sounds good. If you need more juice take a look a the 750TX and 850TX.

same as juggalos advice. i have the corsair 750tx and it has enough power for 2 of your cards.