If your parents are willing to co-sign (and they likely will have to in order to get a good rate or to be approved at all) you have a lot of options out there for you. I personally have been using CitiAssist (
www.citiassist.com) for my private education loans and have had no problems with them yet (knock on wood). I found another site that may be of use as well (
http://www.onesimpleloan.com/private_loans.asp), I haven't checked it out thoroughly, but it looks ok. I'd avoid using SallyMae, they have a track record on not being forgiving at all for late payments (from a recent 60 minutes episode).
As for your poor credit, when the time comes, you will probably need to look into a program where you have to pay a monthly "membership" fee. My fiance is going through the same problem right now he let his accounts go into default for too long a period for the typical credit counseling to work with him (it was over 6 months in default). He just started up with Freedom Point (the people who do the CareFree credit counseling ads) and after three months of payments to your accounts, your credit rating begins to increase. It may be worthwile to look into what your montly payments would be in this program, they tend to string out the payments over an extended period of time...so you may be able to afford this option right now and see an increase in your credit rating in a few months.
Hope this helps a little...