Ah, we got Jamie a crate finally Monday night too! This is like a learning experience for the both of us! Not to mention they look like they should be twins... But its put up and away now, can't get it out to take a pic of her in it. She doesn't really go in on her own still, we're working on it...

We got the crate from walmart that fits dogs up to 70lbs. Clearly an Aussie will never get up to 70lbs, at least mine aren't, Jamie is maybe 40lbs (Charlie is maybe 45, but this is pure guestimation as we don't have a scale to weigh them and they haven't been weighed in over a year).

As long as he has enough room to turn around and lay down and maybe stretch out a little, its fine. As previously stated you do NOT want one that is too big because it encourages some to potty in the crate if you're trying to house train. Dogs don't like going where they live or sleep (hence why mine have never peed on our bed.. we let them sleep with us) so smaller is better than larger, but not TOO small of course.

What are the dimensions on the crate (look on the box) and how big is your Charlie?