I have been using digital cameras for astrophotography for a couple of years now and they are exciting to say the least. But short of owning a CCD camera (or even a CMOS)the modern digital still has it's short-comings. One of the biggest drawbacks of the digital (SLR types included) is that at long exposures you still get too much "noise". You're pic of the Nebula was a good one for the digital camera you have and even better for lunar and planetary work, however I would consider them optimal at best for seep-sky. Don't get me wrong, I think what you're doing is great and a lot of fun, but to just point out that these digitals do incorparate a CCD chip that can handle so much time for exposure before it heats up.
64 seconds is a long time for a digital to expose (I thought 8 seconds was alot before)but having manual "over-ride" to adjust f-stops and such is great. Nice pics by the way and show us now and then what you accopmlish. Have fun and clear(er) skies!!