Need to replace power supply but confused on connections

I need to replace my power supply on an older build. Motherboard is Gigabyte GA-EP45-UD3R. Pin connections in the manual are 2x4 12V and 2x12 main power connector. It's been sometime since my last build, and I find myself confused when looking at the listings on New Egg. I see mostly 20+4 pin and PCI Express connections of 1 x 6 pin and 1 x 6 + 2 pins. Not sure what I should be getting (i.e.: would the 20+4 work in the 2x12?).

I'm looking for 500 watts or more, something inexpensive. Any help in clearing up my confusion and/or any recommended power supplies will be greatly appreciated.

Thanks,
Larry