I am trying to create a few columns in a pre-existing Excel 2007 spreadsheet
that deal with dates. What I am hoping to do is have a first contact date
that is set, and then a column that- using formulas- accurately advances that
date in increments of 30 days, through 180 days. Of course, due to the
variable length of months, it isn't as easy to simply add one month to the
original date.

For instance, I meet client X on 8/4/09. Thirty days later, I need to have
contact with him again. Ninety days after first contact, I need to do a
report. 180 days after initial contact, I should consider his case closed.

Any suggestions?