Just to be absolutely clear about this...

When I refer to Sunnis in Iraq, unless the context dictates otherwise, I am referring to the Sunni Arabs. Same with Shi'ites. So if I use the terms "Sunnis, Shi'ites, and Kurds," I am not displaying an ignorance of the fact that most of the Kurds are Muslims, too. My feeling is that Sunni Kurds will see Sunni Arabs as "the other," rather than as fellow Sunnis, because of their oppressed status for so many years under Arab rule. I think the Sunni Kurds may feel less hostile to Shi'ite Arabs, as they were also under Sunni Arab domination. Persian Shi'ites might be more of a mixed bag, Iran hated Saddam, but they also have an oppressed Kurdish minority with whom Iraqi Kurds might find common cause.