Bill,
Am I oversimplifying what you are saying when I ask if you can just
overwrite all the old data with all the new data? Like,

Sub FixSheet
Workbooks("New").Sheets("Sheet1").Range("A:A").Cop y _
Workbooks("Old").Sheets("Sheet1").Range("A:A")
End Sub

Also, try looking in Excel Help (not VB help) and check out the
functions OR and EXACT. It may require copying and pasting the ranges
to a staging area for comparison and sorting.
I'm in the middle of ten things right now, but when I get a chance I
will look at your files.
Have fun,
Joe