split-window-horizontally by default

[Emory Smith]

i was wondering how i might get horizontally split (ie side-by-side) 
windows by default for "other-window" commands.

when i invoke a command like "find-file-other window" or 
"dired-display-file" from a frame with 2 windows, the other window is 
used automatically (which is fine), but if my frame has only a single 
window available, these commands have to split my single window in 
half.

so what id like to do is have this "automatic splitting" be done 
horizontally rather than vertically so i end up with 2 side-by-side 
windows.

(sorry for such a silly question, i just find the horizontal split to 
be more space-economical on a widescreen display)

thanks, emory