External hard drives

[Glenn R. Fong]

Can I position an external firewire hard drive vertically (upright like a
book) rather than horizontally in its regular flat position?  I bought a new
portable 2.5" external HD to backup my iB/PB, and as small as it is, I could
save some room on my desk if I could position it vertically.  Would this
mess up the HD?  Perhaps related, I seem to recall threads that we should
not operate our books vertically or upside down.