How old is the Intel "GPU"? I remember my neighbor about 3yr ago by now bought a new computer. His kids tried to play Halo 1 on it and could only barely play with EVERYTHING turned down low. The integrated stuff on the current SB CPUs could probably play it on low, but the old GMA stuff probably can't.
BTW, I don't know what you installed, but there is no DX10 for XP, nor does CoD2 support it. DX9.c is all you can put on XP.