I started with a score very close to yours (lower, actually), so there is hope! My current scores are 619 - 652, but it has taken me 2-1/2 years.
If you haven't paid off the defaulted loan, that's what I'd attack first.
The mortgage is helping you as long as you don't have recent late payments.
I'd get a good secured card to help rebuild (ones that will approve in your score band include National City and Elan) while you're handling the existing negative items.
After six months of that, then see what your score is.