don't use the diodes... they're not reliable .. I think I burned one of those once using exactly that technique.
use a proper 3.3v regulatorlike an lm3940 or something (good capacitor required with this part, read the datasheet)
i'll be getting me a proper regulator. but i still don't really understand all this. what's the difference between
a) using diodes to "burn" the volts
or
b) using an lm3940 or similar
???
is it just a matter of proper regulators being more robust?
or why (for example) can i not just "redirect" the 1,7 volts to ground as i am doing with the other pins using resistors?
(that's i'm doing with the resistors or am i missing something?)
i really don't have the feeling that i know what i am doing :-/
still i keep checking my diodes with my cheap multimeter. they seem ok 
i thought of maybe finishing (this) my first arduino project for an exhibition about energy consumption. just a lowfi-interactive 10 frame animation on the display inside a slide viewer. with only 2 weeks left i wonder if i'm still miles away from a solution or just one diode/voltage regulator.
???
thanks for your help so far!