Thanks Montalk and Druid for providing so much info on this....
I wrote an article recently in response to somebody asking me the difference between tropical (Western) astrology and sidereal (Vedic or Hindu) astrology. I find that both systems are useful holographic blueprints through which to examine different things in your life. The Western system is better for examining "Western"-based issues like work, money, commerce, travel, material achievement, etc. The Vedic system is much more soulful, better at revealing karmic energies, stuff you're working on through multiple lifetimes, the shadow side that needs to be addressed, and what you need to balance out within your psyche to become better integrated.
I REALLY REALLY REALLY REALLY wish that Western astrologers were required to study Vedic astrology, since so many Western astrologers are overly cerebral and not very spiritual.
In Vedic astrology, for instance, if you have a poorly aspected planet, the astrologer will work with you to do a bunch of stream of consciousness brainstorming around the issues related to that planet so you can start doing a bunch of different things to embrace or heal that planet's energy within your psyche. So if your Mars is afflicted you'll be learning how to meditate on Mars energies and consciously work to embrace the positive power of Mars.
Western astrology tends to be presented much more as "You've got this crap going on which means your life sucks in this regard, that'll be $200, and you'd better schedule a follow up appointment in a few months so I can tell you how much your life is continuing to suck.' 
Western cerebral type astrologers have little spiritual wisdom sometimes and aren't required to GO there to learn Western astrology. They can just surround themselves in a comfortable world of charts and ephemerides and forget about actually HEALING the influences within the chart.
Whereas Vedic astrology has built within it a much more contemplative, metaphysical, illuminating framework. You won't always find a Vedic astrologer very helpful when you're trying to figure out when you'll land a new job, but you will find his guidance wonderful if you're at a stage in your life where you're turning within and looking at spiritual matters in your life.
Anyway, I wrote about this in this short article recently:
http://www.lipstickmystic.com/mail/astr … ereal.html
Thanks again for all the great info here.
LipstickMystic aka Jennifer