What's the CLI on each card?
Sorry. CL.
Pay them all off. I would start with the lowest balance and work my way to the highest. With a 590 there are other issues on your CR. If you share them with us I am sure you will receive plenty of help. At this level leaving a small balance on one account won't help much.
Starting Score: TU 672 EQ 654 10/20/09
Without knowing what your credit limits on each of those cards, it would be hard to determine your utilization percentage (UTL). The ideal UTL is between one and nine percent. Basically, carry forward a zero balance on all cards with the exception of a small balance on one card. For most people (myself included), this is hard to do. Most of us are works in progress. 
I believe UTL is calculated per card so paying off the one card would help. I would consider putting the money toward the card with the highest interest rate. This will help ensure you aren't paying as much in interest on your next statement. This will save you money as well.
Also, I imagine there are some negative items on your credit report. Have you pulled your free annual reports? If not, I would suggest you do that first (Annual Credit Report website). Look over the reports and find anything that may be inaccurate. If there are inaccuracies, then contact the creditors to fix those errors. If there are COs and/or collections, then you should send PFD for those that are not paid and GW letters for the ones that are paid. This will be help improve your score. There are great example of these types of letters in the stickies at the top of this forum.
@DaBears wrote:Fico doesn't like to see all cards at a $0 bal. It will look like the cards are not being used.Fico has no memory, just a snap shot of each month the cards are reported.
You all are just faster typers than I am... 