To upgrade the processor he would need a motherboard and RAM, and a PCI-E graphics card, and power supply specs have changed since then so that too. Im not sure if they make motherboards with IDE anymore so throw in a hard drive and CD drive, at least my motherboard doesn't seem to have IDE.
So assuming you aren't just streaming slow. You would need a whole new computer. Doesn't have to be a good one but I think you deserve and upgrade to anything.