A couple of questions
1. what size is your monitor
2. what os are you going to use? (u need 64bit if you are going for 4gb of RAM)
3. are you going you be overclocking?
the answer to these questions may alter the choices you make.
Overclocking isn't for newbies. I would suggest reading as much information as you can about it before you attempt it. Overclocking is running a motherboard or processor at a higher speed than what the manufacturer suggests.
If you plan on keeping your computer for longer than four years overclocking can shorten the life of components.