Macro help for compiling data to randomly blank cells

[bigkahuna2187]

I have two colums of dates in one workbook that need to be filled in into one column of another workbook. The column in the new workbook already has values from one column in the workbook, but has some randomly blank cells that i need to fill with the other columns.

Example:

From the old workbook

A
1/1/12
1/2/12
1/3/12

From new scanlist
B
2/1/12

2/3/12

What I would like to do is take whatever date is in the corresponding cell as the blank cell and input that value into the new scanlist to look like this:

C
2/1/12
1/2/12
2/3/12