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Browse credit cards from a variety of issuers to see if there's a better card for you.
Try here to see if you can pre-qualify for anything before getting any hard pulls on your report:
http://ficoforums.myfico.com/fico/board/message?board.id=creditcard&message.id=56760#M56760
Orchard Bank might come up trumps for you - it has served a lot of us here well. Our scores were 543/543/568 when I applied for it. If all esle fails, there are always secured cards.
BTW - are you sure those are fico scores - you can no longer access your EX score yourself exceot through a lender or a few isolated institutions.
Try your question in the Credit Card section. You may get more replies.
Also you may want to think about, being an AU on someone elses card. Make sure they have no baddies and long history.