Power supply efficiency on older model Sun equipment

I suspect many of us have old Sun equipment which
was a freebie ejected from the workplace.  With the
rising cost of energy, and the appearance of new
processors and standards like 80 Plus, I'm starting
to look at my options.  Is it better to save these
old Sun machines from land-fill, or is it better
to prevent coal from being burned to keep them
in operation?

Has anyone seen information on the power efficiency
rating of Sun power supplies?  In my case I'd be
curious about the Ultra 1 I'm currently running
a web site on.

I'm seriously considering retiring all my Sun hardware
and moving to either the Intel Atom, or the AMD
Athlon 64 2000+ (not available yet, but reviewed
at Tom's Hardware Guide), coupled with a cheap
80plus power supply.  I'd probably keep one Sun
box for test drives of new Sun Solaris and that sort of
thing, but not keep any Sun machine on 24 hours a day.

Someone here mentioned the Sunfire v100 was easy on power,
and that is pretty good, but I require something to hold
320GB mirrored drives on my file server.
The Intel or AMD solution is cheap, adequate for home
server loads, and light on the power bill,
as well as not making the house too hot.

--Donald