ATM Newtonian Perfomance

["(RIA) Durkin, Kenneth M" <k.durkin@state.gov>]

I need some advice.  I just started using my home-made 8" F7 Dobsonian
(mirrors purchased from Coulter).  I am quite pleased with the results,
particularly when viewing the moon, which is large and fills the fov (using
26mm and 17 mm plossl eyepieces.  I have also been able to see Jupiter with
it cloud bands and four of its moons (they look like very bright, sharply
focused stars)  and Saturn with its rings.  But Saturn and Jupiter seem
rather small.  I see no difraction spikes, so I think its pretty well
collimated.  Am I getting optimal performance out of my scope?  Is there
some way to make the Jupiter and Saturn appear bigger.  I find that my third
eyepiece, the 7.5 mm plossl loses a lot of sharpness when viewing the moon
(I haven't been able to get it on Saturn or Jupiter), is not very forgiving
of vibration or air current, and is difficult to keep in focus.  Also,
though I haven't tried it yet, should I be able to spot Uranus and Neptune?
Thanks,  Ken