Neat-
I actually agree with Muleman but perhaps with a bit of a different view. As the mother of two boys, I know I am overly protective and yes, I do worry about the girls they date and the friends they associate with... what mother doesn't? But what worries me more is how silly kids today can be when it comes to their relationships and view of sex.
I am pretty sure one of my sons is not a virgin anymore and doubt his girlfriend has even a basic understanding of contraception. When I tried to discuss my concerns with his father I got the "boys will be boys" wink, wink speech. I almost slapped him. Excuse me? Are you really ready to have grandchildren? And what happened to our hope that our son would go on to becoming a doctor or dentist or the next Bill Gates? It is a lot harder when you are responsible for a baby. Oh, and assuming that abortion is an option, did you Mr. Cheapskate want to help pay for it? Might cut into that golf vacation you and your buddies have been planning for the last 6 months.
At least my son's girlfriend is white and her parents are pretty much like us. So I know that if there is a problem, we will not be dealing with the cultural and racial issues that would occur if she was black.
So, Neat, if the parents of your daughter's boyfriend are not friendly to you, look at it from their point of view. They certainly do not want their son have his future hurt by getting involve with the "wrong" sort of girl... and yes, I mean "white", and worse, they may have little in common with you and how do you approach each other if some was to happen that would affect both families?
I am not sure how you break down barriers, I am not sure they want them broken down, but I do know, it is your daughter and not you who will help break them down if their relationship becomes serious. If they view her as "respectful" and not "white trash" they may accept his dating her. I am not sure that I was ever able to win over my BF mother but at least she stopped being hostile towards me when she saw me being respectful to her and subservient to her baby boy. In the mean time, as Muleman suggests, "...don't try and push it you might really turn her unsympathetic."
Oh, one last thing, and I know it sounds silly but I really mean it... teach your daughter to cook! I am not a great cook but I enjoy doing it and the fact that I learned how to make some of my BFs favorite dishes really helped with Mam-ma. I have talked to other women in interracial marriages and relationships and they all agree-- learn how to cook!