The factors slowing you down is 4gb ram and your CPU. Yea...definitely get a core 2 duo. Like fade2black2004 said....it does slow down your system, because windows xp can only handle 3gb. For optimal performance, stick with 2gb.
3770K | ASUS STRIX GTX 1080 | DDR3-1600 16GB | CORSAIR 650D | CORSAIR HX 850W | CORSAIR H100 | SOUND BLASTER Z | ASROCK EXTREME4 GEN3