Vista - WinExplorer > Opening folders, not files, on single-click

I read through the post about opening folders in Win Explorer, but I have a
slightly different problem I'm trying to solve.

In XP --- somehow --- I have it ideally set where I can expand folders in
the left Panel with a single click, but to open a file I dbl-click.

In Vista however, the process is reversed where the folders in the left
Panel do not expand, but the do in the right Panel on sgl-click. That's not
so much a problem except that I cannot select a file in the right Panel
without that file opening.

So, ideally this is how I'd like to configure WinExplorer that I can't
figure out:
-Left Panel: sgl-click to expand folders.
-Right Panel
a) sgl-click to expand folders
b) dbl-click to open single files.

Is this possible?

thanks for any help, direction, or advice!