You can get two things accomplished if you upload them to google music.  It'll add them to your google music cloud storage account (there isn't a total size limit just a song count limit, it's 20k maximum 300mbs per song) that way you always have the files encase your hard drive dies or whatever.  This also lets you take your music with you and listen to them through the internet on your phone or whatever.

 

More importantly when you download the track from their servers it will be in mp3 format, if I'm not mistaken it ties you track to the track google has, to help speed upload times up.  For instance if you upload track a, and google has that track it will just give you the track google has which is in mp3 format.   

 

Forgot to mention you need to use google's media manager for wma, it won't work trying to upload from the browser. 

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