I have an HP Pavilion p6803w. About a year ago i wanted to speed it up so i put a Radeon HD 6570 and a 750w power supply. I am thinking about maybe building my own gaming pc for around $550 but i want to take small steps. I was thinking of buying a new processor but since my motherboard is AM3 i don't know if i should buy a $150 dollars AM3 processor or for about $180 dollars buy a processor and a motherboard. I am hoping to slowly build a computer that will play next generation games like Thief and Arkham Knight. So what should i buy or not. Thank you for you time.