For motherboards, you can chose between several "chipsets". I would recommend a Z68 or Z77 chipset motherboard. The chipset is often in the name. The Z77 is newer, so I would recommend that over the Z68 one, especially if motherboards are at around the same prices.
There are several good motherboard manufacturers.
Asus and ASRock are basically the same company. I like them. I have an Asus motherboard right now myself. I will buy a new ASRock Z77 motherboard myself next week. (When I buy my new CPU).
Gigabyte and MSI make excellent motherboards too.
Usually manufactorers make several different motherboards with the same chipset. The difference is often that the more expensive motherboards have more exotic features. Usually you don't need those. So the cheaper motherboards are just as good for you. (As long as brand and chipset are the same). E.g normally you can add 6 harddisks (or SSDs or DVD-players). And with the expensive board you can add 8 or 12. Or with the expensive board you can do SLI or CF (having more than 1 videocard), while with the cheaper motherboard only 1 videocard.
Example:
ASRock makes 10 different Z77 motherboards.
http://www.asrock.com/mb/index.us.asp
The ASRock Pro3 costs 80-90 euros (in my country).
The ASRock Fatal1ty Z77 Performance costs 150-160 euros.
What is the difference ? One more DVI-D output (which doesn't matter, because we buy a separate videocard anyway). Some more robust capacitators. Better "build quality" isn't gonna give us more fps. The expensive board doesn't even have more PCI-E 16x slots (which would be good for SLI/CF). So I guess the Pro3 is just as good as the Fatality for most users.
So I recommend the ASRock Pro3 Z77 for people who build a new PC with an i5 or i7 CPU.
I might buy it myself. Or I might buy the ASRock Extreme 4 myself (125 euros).
That being said, the other brands (Asus, Gigabyte, MSI) aren't much worse or better, imho. I just like ASRock (and Asus) myself.
====
About the powersupply, I am not sure what to recommend.
There are many good brands. And unfortunatly also many not good brands. Pick a brand that is a bit known, not just any unnamed brand. CoolerMaster, Enermax, Nexus, OCZ, Seasonic, Silverstone, they all make good PSUs. I am sure I've forgotten a few brands. And I am sure other people on this forum will disagree.

Usually a good PSU in the 500-650W range will cost 40-60 euros/dollars.
Then try to figure out how much wattage you need.
There are many sites that help you there.
Example: http://support.asus.com/powersupply.aspx
Select the components you will have in your system, and the website will give you a minimum wattage. I think the recommended wattage here is pretty high, so you don't need to add extra, "just to be safe".