I live in Northern California.  My water is very hard.  We live in a
new home and are looking to purchase a water purification and water
softening system.  Researching this has been very confusing.  However,
Advanced Water Products knocked on my door and they were selling
systems.  They are a little more pricey, but very familiar with the
issues around installing it in MY home.  I am okay with paying more
for a superior product.  I am not interested in dealing with Sears. 
Their service is awful.  My question is 3 part:
Are you familiar with Advanced Water Products? (I already have their
website, I don't need it www.advancedwaterproducts.com)
What other options exist for getting a good water softener and water
purification system installed?
What issues should I consider when making the decision?

There are ALOT of issues to take
into consideration. Mainly the
cost of the initial installation,
if you're not doing it yourself.
The cost of the initial equipment.
And the cost of maintenance, and
refilling of any media that gets
used up.

Have you done a complete water
test yet? This is very important
to make sure you aren't getting
too much or too little softening.

I don't know Advanced Water Products,
but I do know water conditioning.
In NC, we had some of the WORST
water ever, even with a REALLY
deep well. Several hundred feet.
Rust, calcium, and worst of all
Oxides of sulfur. ICK. VERY
elaborate water system there.

Basically most systems will be
alike, since they are for the 
same conditioning basically. Let
me know about the water quality
test.

-AI

Some things to consider include whether you are getting water from
your own new well. I presume you are and that brings up an interesting
problem. I have a 15 year-old well which was so bad when drilled that
there is an extensive filtering and conditioning system installed by
the previous owner. This required adding caustic soda and frequent
periodic flushing of two conditioning tanks.

I bring this up because the water quality has improved so much just
from being pumped extensively that only one conditioner tank is now
functioning and it only needs recharged/flushed occasionally.

Consider this and ask neighbors if their water has improved over time
and, if so, you should not get too carried away with a very expensive
system which may only be needed a short time.

If you can get away with less you can use a reverse osmosis unit under
the sink for cooking and drinking water.
 
I strongly recommend that you talk to other local residents and
perhaps the local drillers before talking to the water conditioner
people.

BTW, I agree on Sears and Culligan, at least in this area.

Good luck.

Since it's always important to understand the basics, I thought you
might want to glance at this "How it works" page for a 30-second
primer on how water softeners work:

http://www.howstuffworks.com/question99.htm

This is just the basics to skip it if you already know about replacing
calcium and magnesium ions with sodium ions.

One thing to think about is that regenerating a zeolite conditioner
will use a lot of water and create a lot of salt water you need to
dispose of someplace. However I can report that even after years of
the salt water going into a cow pasture it hasn't killed the grass so
it's not as bad as it might seem. It could cause problems in a septic
system though.

You might want to use the directory at:
http://directory.google.com/Top/Home/Consumer_Information/Appliances/Water_Filters/
Note the buyer's guide, fourth in the list.