Excel 2007 : Conditional Formatting a Date Table?

Hi,

Could someone please help me on Conditionally formatting a date table? I would like to make a table, and have dates that are within 1 month (for example, may be different) of the current date to turn red.

For example
system date shows 4/17/09

I'd like any date in the table that shows 5/17/09 or earlier (up to 4/17/09 of course) to turn red.

Any ideas? Thanks!!