Lets say you want cells A1:C1 to be greyed out when A1 has a value of 1.
Highlight columns A:C and select Format-Conditional Formating. Select
Formula Is and insert this as your formula
=$A1=1
include both equal signs. hit the Format button to assign the formatting
(select the Patterns tab to assign a background color). Now in any row when
A has a value of 1 the row will be greyed out.

If you want a specific text use a formula like
=$A1="text here"

"strider" wrote:

How do I highlight a row based on the value in one of it's columns.
Lets says I have a list of tasks that I have to complete. One of the
columns is the status of the task. When I select the Complete status in that
column I want the whole row to automatically be grayed out. Is this
possible? How can I do this?