changing background color in a single cell depending on text shown.

Hello,
New to the forum, have used the search button and done internet search and do not seem to find what I am looking for.

I have a cell that I want to change background colors depending on the results in the cell. For example if the cell reads Valid I want the background to be green. If the cell reads Invalid I want the background color to be red.

I can make it work with conditional formats as long as the cell contains numeric values, but not when it reads text.

I have used excel for years for very simple things, but this is kicking my butt. Any help or advise would be appreciated.

I have attached a sample work sheet or what I am trying to do.
example.xls

Wow thanks for the quick responses and the help. You guys are far better at this than I am. I figured it could be done, but that solutions never crossed my mind, obviously.