[gDesklets] How do I install the Rhythmlet sensor?

[David Barrett <dbarrett quinthar com>]

How do I get the Rhythmlet desklets to work on a fresh Ubuntu 7.10 
install?  Specifically, each time I try to add, I get this error:

Could not find sensor 'Rhythmlet'
/usr/share/gdesklets/Displays/rhythmlet/gfx/LT-Display/CornerRhythmlet-bottomright.display
A sensor could not be found.  This usually means that it has not been 
installed.

How do I install this?  I apologize for the basic question -- I see that 
a lot of people have had similar problems, but I haven't been able to 
find the answer.  Thanks!

-david