To begin, read this article and find out where you end up in terms of what you need. These days not everyone needs a super awesome computer to get around. And the CPU is not the most important part of your computer any more.
http://m.lifehacker.com/5684015/craftin ... -spec-list
This picture, as it were, is very helpful to anyone who does decide to build their own computer. To my knowledge it is updated from time to time, so check the date at the bottom just in case. This has been posted before, fyi. It has a lot of great information on more than just how much something might cost. If you are unsure of brands, just read the bottom area of it. It goes over a few things on each manufacturer, as well as what to pay attention to when purchasing each component.
And finally, it doesn't hurt to ask any of use here if you are still unsure.