If you want to get really fancy ..triple-paned windows can be used, but the benefits of a triple may not outweigh the costs.
aluminum has a very strong tendency to weep ..meaning gather moisture on the exposed areas inside the house causing slow and gradual water damage to molding, drywalls, etc. (at least the aluminums in my rental house do and my parents house).
Fiberglass, i haven't done much research into nor have i seen many.
Hope that information helps. Feel free to contact us with any other questions.
Lynn911 Dallas Realtor & Consultant, Loan Officer, Credit Repair Advisor
The Michael Group - Dallas Business Journal Top Ranked Realtors
You'd want to stay away from aluminum windows due to the thermal bridging. Triple glazed windows are also probably not the best way to spend your money. Your better off taking that money and putting into additional insulation in the walls and attic. Go with a combination of spray foam and dense pack cellulose.
Hurd is a little known brand that makes great windows. Check them out: http://www.hurd.com/
I've also included a few additional web sites below that may give you some good "green" building ideas.