Don't bother with your camera.. Soapboy is right.
If you have an Athlon XP in there, its Socket A, which is 462 IIRC... maybe 464??
Socket A housed Athlon, AthlonXP, Duron, and some Semprons
Socket 478 is P4/Celeron
Socket 940 was AMD's server line that housed older FX series chips, and Opterons I believe.
Socket 754 is the first A64 socket, and is now the "low end" A64/Sempron socket.
Socket 939 is the current "top" socket for AMD, which uses the latest A64/A64 X2/Opteron/FX chips.
And socket 939 is on its deathbed.... don't expect a whole lot more jumps in processor speed on the s939 platform. AMD's new socket will be out soon.