Hi Murphy
A few comments, pretty much as others have said:
* Not much point shooting 10mins subs from suburbia - your signal to noise is limited by background light pollution - you really need to get away from Brissy if you're going to "let rip" with anything more than 5 min subs
* The 450D is quite capable to giving a nice result - here's an example from dark skies with an 8" Newt:
M20
* Don't forget you need lots of subs to help cope with the noise, probably 2 to 3 times as many from the 'burbs vs dark sky
* Even then you won't get the faint blue regions if they're only as bright as your background sky....
* An MPCC would be a valuable addition and probably an IDAS filter too
* How are you focusing? Do you have a Bhatinov mask? You want it razor sharp with good collimation.
* 450D - remember in winter you will have noticeably less noise than summer - all the better to make the most of the bright nebs in the milky way! (Edit: I see you're cooled already!)
Its getting there!
Rob