What PSU to use for my new build?

Get the OCZ ModXstream Pro 600w (this is what I have on my system) or the Cooler Master Silent Pro 600w.

http://www.hardwaresecrets.com/article/936

Edit* FYI I have the same video card, HIS Radeon 6770, on my i5-2500k system OCed to 4GHz on stock voltage with Gigabyte Z68. Wattage for my build is about 450w. Since you got the FX4100, it will consume a little bit more power but I'm sure it won't be over 500w. So 600w PSU will be good enough even you decide to Xfire wih another 6770 in the near future.

http://www.tomshardware.com/reviews/radeon-hd-5770,2446...
5770 Crossfire System Power Consumption
Idle = 109W Load = 324W
This system is using an i5-750. But I think that shows that 6770s don't use a lot of power, so the only reason to go above 450W is to overkill or to give yourself lots of upgrade options. Or if higher wattage units are better priced and higher quality/more feature rich than lower wattage units.

Rosewill Capstone 80Plus Gold series; the 450-650W units are all at or below $100.
550W $80
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

XFX Pro 650W Core Edition 80Plus Bronze $80 ($30 rebate)
http://us.ncix.com/products/?sku=59616&vpn=P1650SNLB9&m...

PC Power & Cooling Silencer MK III units are good if you want a modular PSU.

Thanks alot guys. I should mention I live in Australia so I am quite limited to decently priced parts. I found the OCZ ModXstream Pro 600w for $85 so i am gonna get that i think.
I'll probably be upgrading to the next generation video cards when they come out. as theyre supposed to be more power efficient so I should be alright with this psu.

Oh nice. Will that give me much room to upgrade in the future? Say if i were to get a more powerful graphics card and processor?

yeah any singlr graphics card will be fine even a anything up to a gtx 480/580 and ill be damned if the newer graphics card draw more then any of those 2 and any cpu will be fine

excellent. thanks for the help i'll be gettin the Antec Neo Eco 520C probably this week or next.

Best answer selected by mathuey.