> Well, from my research and personal experience, it all comes down to
 > matter
 > of preference. NASDS is a good certification program, as well as long.
 > You
 > cover a lot of material over a two to three month time (every weekend)
 > but
 > when you are done you have an advanced open water certification. There
Slight mistake here.  NASDS offers an open water certification (24 hrs of 
class/pool) work, and they also offer a separate Advanced open water 
certification.
Generally, the open water class is covered in one month (two weekday evenings 
6hrs/week or 4 Saturday's (all day)) unless someone has extended the schedule 
at some shop.  If that is the case, and it doesn't fit your schedule or time 
frame, then look for a different instructor.
Please note, I am a NASDS instructor, and the headquarters to NASDS is right 
across the street (literally) from "The Dive Shop" here in Memphis, TN where 
the infamous Doug McNeese can be found.
NASDS's program is extremely nice.  NASDS places more emphasis on safety than 
any other agency striving to teach folks that owning and becoming intimate 
with your own equipment can prevent many emergency situations.
The Advanced Open Water Certification class teaches night diving, deep diving 
(to 100 feet as NASDS members don't dive deeper than 100 feet), and 
navigation.
Beery Miller
NASDS OWI 3208
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