Raptor...
I am going to try to not get technical, so bear with me.
Do you know what type of motherboard your brother has?
Most motherboards are either socket370 (has a square usually white socket that processor plugs into), or Slot 1 is normally a longer connector (usually black).
Depending on what type of motherboard it is will determine the outcome.
If it is slot 1 motherboard, you have two choices. You might be able to find a slot 1 700 mhz, or you might have to get what they call a Slotket.
A slotket is in the shape of a slot 1 card and allows you to place one of the newer P3 FCPGA processors in it.
Good Luck
ps just let us know a little about the motherboard and if you know what the speed rating on the memory is.