The simplest!

1) What CPU's does your motherboard support? Do you have the mobo booklet that gives this inf? If not, identify your mobo and see if you can get the details from the internet.

2) IF it does support a 500MHz CPU, is such a CPU available?

3) If yes, then you will usually have to pull out the old CPU, do some jumper changes in the motherboard, plug in the new CPU and you are thru'.