I've got a newer book (2007), and the Illustrator conversions are off by almost 10% in some cases. I also have the Art Directors Toolkit for this purpose, and I've learned not to trust this either. I'm not sure if I have a setting wrong in Illustrator or what but I always go by the PANTONE book for my conversions.
Oh, and I'm sure it's too late but my Color Bridge book shows 7408 as 30M and 99Y. Not that big of a deal, but it is different.