Sof****er has two sides to it, real stuff, and comfort issues. Hard
water requires more soap for the same level of cleaning and builds up
on all surfaces including the inside of your pipes eventually blocking
flow so much they need to be replaced and it aint cheap. Soft water can
be very nice for skin and hair, but some people don't like the
slippery, "I'm not rinsed enough" feel. Some people love it and are
never happy with hard water again.

Whole house.
A larger tank system goes on the main cold water line as it enters your
house and all water is softened.

Hot water.
A smaller unit (maybe 1/3 the size) just before your hot water heater,
and it softens just the hot water. Many people do this either to save
money, or they prefer the blended less slippery water. No protection to
your cold water pipes, and most of the benefits of full sof****er for
laundry and bath uses.

Look in the phonebook under water softeners and get a monthly contract
with a free installation to see how you like it. In 6 months for a
$100 you will know for sure, and can take your time shopping for a unit
to own if you want to keep it a long time. Also a real licensed plumber
has to do initial installation, but a "handyman" type guy can do the
replacement.

Final note.
The water softener has two parts, a brine or salt tank, and a resin
bed. The resin bed is kind of like a battery that gets charged up with
calcium it removes from the water. When its full you need to regenerate
the resin by running salt water through it. Thats what the timer and
stuff does. When it is all working fine you won't notice a thing. In
the middle of the night valves switch around and salt water is sucked
out of the brine tank, through the resin bed, and out a drain (often
the laundry drain). Once the brine tank is empty, the water continues
to flow rinsing the salt out of the resin bed, then the valves switch
back to normal. The drain is closed and the brine tank refills (just a
few inches of water really and a toilet tank float shuts it off), and
its ready for use when you wake up in the morning. If the valves mess
up a bit, or the cycle isn't timed correctly, you can end up with some
sal****er in your lines. As long as it doesn't happen often, chances
are you will never even notice. 30 seconds of water running in the
shower and the lines are flushed with new water anyway. I like to let
the shower spray on my teeth, and maybe two or three times in a year I
notice a bit of salt taste for the first minute or two. Its not an
issue to me, but I do use reverse osmosis filtering on our drinking
water which would remove any residual salt or anything else.