In which case you are going to need new cpu/motherboard and DDR3 ram. Whats the budget? Also, what's the power supply that you have?
So, new motherboard, cpu, memory and a psu then. Going to need a budget. No good speccing something thats way more than you want to pay. What GPU will you be using?
if its a slow build go for higher end stuff ? i got my self i7 4470k 3.5 8gb of corsair ram and a mobo for £270