Here's another handy Pantone tool. For Microsoft Office users, Pantone themselves makes a plug-in utility called the Pantone Office Color Assistant.
http://www.pantone.com/products/products.asp?idArea=3&idProduct=72
It puts a new toolbar in Word, Excel and PowerPoint that allows you to precisely pick your Pantone value from three Pantone color libraries. You can color text/fonts, backgrounds, objects including Excel charts, and lines. It also will work with FrontPage, but currently doesn't work with Publisher (unfortunately). It will not color text in Office 97. A 16-bit (or higher) color display is recommended, and colors are displayed on the monitor in sRGB. Easy installation, although their help files note a small quibble with Office XP.
I've had it for about three months and find it relatively useful. If you have a client in marketing who is persnickety about their Pantone colors, they will love it. But, as Docusulant cautions, what you see in print depends on the quality of your color engine. Speaking from my experience trying it with a Ricoh 2228 and a Ricoh 3224, the Pantone Office Assistant put me a lot closer to the value I wanted than trying to determine a custom value in Office's palette.