Conditional Format for a Range of Cells

Hello, I am trying to apply conditional formatting to range of cells (in Excel 2007) as follows:

Column A contains several numerical entries; this is the data.

Column B also contains several numerical entries; this is the lowest that I would want the data in the same row in Column A to be.

If an entry in Column A is less than the same row entry in Column B, I want the background of that entry in Column A to turn red.

I've tried the basic way of conditional formatting, by highlight the cells I want to be formatted, clicking on Conditional Formatting, selecting Less Than, and selecting the range of cells I want to see if the data cells are less than. But Excel complains that it can't receive a range of cells for the conditional formatting.

Even while I'm writing this out, I'm thinking of a way that I can probably do this (by subtracting the two in another cell then comparing that to 0). But it seems to me that there should be a more elegant way in Excel to do that.

Thanks for any help you may be able to provide.

Thanks, that should work!