Convert Column Headings To Cell Value In Large Spreadsheet

I have a very large spreadsheet that is a consolidation of approximately 105 separate of contacts lists. The new consolidated spreadsheet contains demographic data, and a column for the name of each of the 105 lists. Each contact in the consolidated list had an "X" placed in the column if they were a member of that particular list. Each contact can be in more than one list. This is not very useful for me.

Here's a visual representation of the current list along with what I need:

FName
LName
Address
Phone
City
List1
List2
List3
List4
List5
List6

[Code] .....

I would like to add a column to the spreadsheet and call it "Source"

And then have a macro or VB script to do the following:

1. As shown above, put the column name (ie "List2") in the "Source" column whenever there is an "X" in that row for the corresponding Column.
2. Because each contact can be in more than one list, I need to append the column names so that "Source" column contains all of the column names (Lists) that had an "X"
3. Once all of the list names have been added to the "Source" column, I will delete the list columns.