I agree Mike about using Pantone spot colors when matching a color is absolutely critical.

But if your printing process is CMYK, or if you are trying to match a Pantone color in a print ad or brochure, and an additional color or colors is not an option, then you have to try to do your best.

What is frustrating is the differences between applications in Pantone to CMYK approximations. I gave two, one from Xara and one from Illustrator. Each is different.

I used to use TruMatch for matching Pantone colors as this way you are looking at what CMYK color comes closest.