Condtional Formatting Based on Another Column's Data

I have two columns, A and B. I want there to be data bars in column B that reflect the magnitude of the difference between the two columns. If the value A-B (for a given row) is positive, I want the cell in B to turn green, with a data bar that reflected the magnitude of the difference. If the value is negaitive, I want the cell to turn red. I tried writing a formula that would do this univerally for all of the rows, but could not figure anything out. I created a third column C, which calculates the value of A-B and applies data bars to it. I essentially want the data bars that show up in column C to show up in B. Is there any way to do this?

Thank you in advance

I'll give a clearer description to try and help shed some light on the problem. Column A gives the ranking of a team in 2011, and Column B gives the ranking of that same team in 2012. If the value in B is greater than that in A, then I want two things to happen:

1) A red data bar appear in B, as the ranking is now worse (a higher value, but a worse ranking)
2) The size of the data bar to reflect the magnitude of the difference

To clear up point number 2, here is some real data from my file: the value in A1 is 1 and the value in B1 is 6. Therefore, the ranking for this team decreased by 5 from 2011 to 2012, so I want there to be a red data bar in cell B1. The value in A2 is 4, and the value in B2 is 1. Therefore, the ranking for this team increased by 3, so I want there to be a green data bar in cell B2. However, the difference for the first team has a greater magnitude (5) than the second team (3), so I want the bar in B1 to be longer than the bar in B2.

Hopefully this makes more sense. Thanks.

That seems to be headed in the right direction....

If you scroll to the bottom of the second link, you see the side-by-side comparison of data bars for the %Profit Change in Excel 2007 and 2010. What I want is the data bars in the 2010 version. I understand how to get them to show up for a specific column, but not how to get them to show up in one column based on the data in another. In the example in the link, it would be equivalent to having the 2010 data bars for %Profit Change show up in the column Sales Amount. (i.e. ColumnSalesAmount would be formatted conditionally on Column%ProfitChange)

I want to format Column2012Ranking conditional on Column2011Ranking. Perhaps this better illustrates what I am hoping to find.

Thanks again