Rolig, I think your mother is perfectly correct in her assumptions of thirty years ago. The Deep South looks down on the upper South (or the urbanized South) as not being "real" enough, while the upper South (Virginians have always been guilty of this... and I am an adopted Virginian ;) ) looks down on the Deep South.... Just the way it is.
Just as racism within the African American community is kind of a secret from outsiders (non African Americans), so is the kind of "you're not a REAL child of Dixie" among southerners. And, for that matter, the Italian Americans of my hometown—the ones from northern Italy tended to look down upon those from southern Italy, here in the United States, where outsiders would have seen them all simply as "Italians" or "immigrants."
Sorry to get off on a huge tangent there... Anyway I think you're right—the more urbanized/industrialized an area is in the South (e.g. DC suburbs, Research Triangle, Atlanta), the less culturally, identifiably "southern" it is. You can almost just follow the Interstates to see where it's been transformed.
It's fascinating what you say about Alabama and Mississippi. My mother, a true Southern belle from Danville, Va., tended to look down on these states as being uncultured, redneck, and crudely racist (as opposed to her own, more genteel racism). But that was thirty years ago. I can see why those in the Deep South would believe Va., N.C. and even Ga. are Yankified (not sure that is true of S.C., though). But once you get outside of the DC suburbs and the Raliegh-Durham-Chapel Hill Silicon triangle, and Atlanta, I think you're still very much in the Old South. That is true even of Southern Maryland and much of the Eastern Shore, as well as rural Delaware. (At least back in the 1990s, it was.)
Rolig, not to contradict but add more information, in my experience the "Old South," today, consists more of what I'd call the Deep South: Alabama, Mississippi, Tenessee, maybe even Louisiana and Texas. Even though, for me, the term conjures moonlight and magnolias (as the saying goes, or went) which in turn conjures the Carolinas, Georgia, and Virginia, when I lived in Miss. lots of people insisted that the only "Old South" that was left in the entire country were AL, MS, and TN. The rest of the former Confederacy, they claimed (such as VA, NC, SC, even GA!), are now too Yankeefied. *shrugs* I guess wherever you live, you can always look down on someone else...
At any rate, yes, there is definitely an Old South! In fact there was just an article in Newsweek about it not too long ago... *looks for a few minutes, then gives up*
Oh yeah, there is definitely an Old South. Ask any white Virginian (outside of the DC suburbs, which don't really count). Basically, geographically, the "Old South" refers to Virginia, the Carolinas, Georgia, and traditionally, Maryland and Delaware – the Southern states that were among the Thirteen Colonies. But it is more often used to express nostalgia about a fantasized antebellum South evoked by such books as Gone with the Wind, where the (white) men are all honorable, courageous gentlemen, the (white) women all refined Southern belles, the blacks are happy to have such fine, respectable, and kindly people as their masters. Like many of the places in my "States of Mind" list, the Old South never existed except as a dream.
Is there a 'new' south? Is it a place more south than the previous south? Or is this like the 'new' math? Or is it more like 'New' Zealand? Is there a 'Zealand?' Or an 'Old Zealand?' 'Cause I've never heard of either one. *peach flip only has about 15 minutes left...*