Re: motherboard LGA557 mATX m5167
I think you mean LGA775, not 557. Intel only made an LGA775.
That socket is pretty old, you might be better off finding a new system from Best Buy (depending on their use) or building a new one. Contrary to what others on this forum lead you to believe, if the user is just a standard user, and they don't care about horsepower, you can pick up a pretty decent PC for <$400 these days at the retail stores.
Problem is, most Socket/LGA 775 boards these days used are going to be $150+, and I've seen some going for as much as $450 even when they only sold for $99 brand new a few years ago. Have to weigh all your options.