winXP SP3 not installing

i have been trying to update my system to sp3 from sp2, even in automatic updates it failed as its getting stuck after a while and i downloaded sp3 and tried to install, same problem. As i have heard that AMD processor is having some problem with sp3 installation and also i read in sp3 system requirements that it wont update in 64 bit windows xp.

my configuration is AMD Athelon 64 x2 Dual Core Processor5000+, 2gb ram, Nvidia GeForce 8500 GT

kindly help me out

If SP3 can't be installed in amd 64 bit then how come SP2 is there, which is lesser OS?? By your answer it seems not possible to have sp3 in my system