You may want to look into power supplies that are higher quality. Some of those combo deals have crappy power supplies. Anything from Antec, Silverstone, Thermaltake just to name a few will run good for overclocking. There are a ton of good power supplies out there, those are just three companies that come to mind.
As for motherboards, Asus and Gigabyte make some good boards that overclock well and do not cost a lot. A board with a P35 or P45 chipset would work fine.