Extreme noob electronic question

[Marc Nostromo [M-.-n]]

I'm still slightly confused between polarized versus non polarised capacitors :)

I'm going to need a voltage regulator to bring down 9v to 5v with a
LM7805 using this rough schematics

http://snesdev.antihero.org/wp-content/uploads/2008/03/lm7805.gif

I undestand the capacitors are used to stabilize the ac changes in the
DC supply. Does that mean I can't use polarised caps ?

Because my impression is that the voltage will no matter what be
higher than the ground so polarity should not get in the way.

Does all that make sense ? :)

Thanks
Marc.

--
http://marc-nostromo.com