Closed-source, possible?

[Davis Chord]

I'm a fairly new Python developer, so I hope that some of my ignorance in
this area is understandable. :)

I'm developing an application, and I'm uncertain about releasing it as
open-source. The main reason I thought about open-source was because ever
Python program I've seen is, truly. Doh.

I've heard/seen/used the pyc program that turns your .py files into .pyc
files, but I'm wondering how easily someone can get to your source from
these compiled files. If it's not possible to have a portable progam thats'
source cannot be easily accessed (or at all :P), then open-source is just
easier.

Thanks!