if you can wait two weks the new ib i3 will be out. same price as the sb chips just lower wattage and slightly faster.
with mb it simple...there the chipset for overclocking (x68 and 777 chipset) for the k chips. and there the cheaper non overclocking chips the h and b chipset. under the chipset there two main sizes of mb the atx and mini atx. the mini atx are made for new gamers or web surfers. most of these boards have two dimm slots and one video card slot and a few usb ports on the back. these are system for people low on cash and or ones that build once and leave the system alone. the larger atx will have a longer warranty some times..more ports or more bling then the cheaper mini boards. (like the z77 sabertooth.).
most mb vendors make the mini to fit in the 80-140 price range. then the full size are in the 150-400 price range the 300-400 most time are e-atx mb wiht two cpu slots or made for qaud sli/crossfire. most gamers will be fine with 8g of ram. if you get a two slot mini mb then put two 4 gig dimms in. just make sure you use a good cpu heat sink and power supply with your build.
heat and bad power are the two killers of computers.