Populate BPM

Could somebody advise me of the best way of getting the BPM values populated in tags.

I have17.000 MP3 where I would like to know the BPM for all of them. Is there a tool which can update these values.

Thank you in advance for any help.

The only tool I know is BPM Analyzer

http://www.mixmeister.com/bpmanalyzer/bpmanalyzer.asp

DetlevD noted that the tags have to be V2.3 as otherwise you loose data.

Here is a list:

http://www.bpmdetection.com/

supports BPM and KEY detection. Great tool and a lot of big name DJs use it. *coughs David Guetta uses it along with sebastian Inrgrosso, kaskade and Markus Schulz (the list goes on).