I'm really having a hard time understanding this.  Can someone confirm for me whether I'm getting this right.

So a person owes $10k on his credit card.  He pays $1k to the balance.  90 days later he files bankruptcy.  If the trustee determines this is a preferential transfer then the credit card company can still get the full $10k? 

If this is correct, why would some creditors get preferential treatment just because they were paid prior to the bankruptcy??

Also the term "preferential transfer" - what is being transferred?  Money?  Assets?

 Any help provided would be greatly appreciated.

I think it means that if deemed preferential than the trustee can get the money back. Think of it as the debtor giving preferential treatment to a creditor and how that would not be fair is he is filing for bankruptcy. Because it's not fair, than the money would be set aside, or taken back.

Like you said though, a preferential payment is for a payment made within 90 days of filing, for an antecedent debt, and results in the creditor getting more than he would have if received had it been settled in the terms of bankruptcy.