Just a brief bit on definitions: Arabs are natives of the Arabian peninnsula (or their descendents, regardless of nationality). Afganis are not Arabs, nor are Iranians. Arabs can be Moslim, Christian or Jewish. Moslims/Muslims can be of any ethnicity or nationality. Sikhs are neither Arab nor Moslim.

BTW, I believe I read somewhere that naturalized citizens of the US have a lower per-capita crime rate than the native-born, but I'll be darned if I can find the source of that statistic.