I know a lot of black people with my last name. Especially in the city where I used to live, my first name is becoming a popular baby name for blacks. Not that that is a bad thing, but I was called for interviews by black-owned firms and corporations there, and I think they were fully expecting a black person. Margaret is definitely not a black name, so maybe it would be a good idea, granted I don't get married in the next few years, if I change it if/when I move back. It would help cut down on confusion.
I thought about using my middle name as my first, but it's one-syllable and I don't like how it sounds when used alone with my last name.