There isn't really much to upgrade on your PC. Your motherboard is probably limited to a 1066mhz fsb CPU, so there is really no better CPU for you to spend your money on, at least being worth the extra money for a minor increase in performance. You can bump up the memory to 4-8GB, upgrade to windows 7, and upgrade to a video card like the R7-260X. That should give you a PC able to play games at a reasonable setting. If you didn't have a dell motherboard, you could overclock that CPU to 3.4Ghz, I did it on my old system with a Biostar board.