Transform rows into columns in VIM
===

I have a data file like the following:

    ----------------------------
    a b c d e .............
    A B C D E .............
    ----------------------------
But I want it to be in the following format

    ----------------------------
    a A
    b B
    c C
    d D
    e E
    ...
    ...
    ----------------------------
What's the quickest way to do the transformation in VIM?
Thanks.
