Changing a PC’s Speed

I have an older PC that was built for me. Its speed is a little less than 1 GHz. I have another one with greater speed, but I have dedicated this one to the net. I need greater speed for Skype and some other things. Is it possible for me to purchase a AMD Athlon 64 X2 6000+ (3.00 GHz) for $235 that TechExec2 suggested? I now have an Intel chip. Would I need additional parts for this speed upgrade?
Thanks,
Bug711