Walmart started selling DRM free MP3 music in August last year, before that its online music store use to sell DRMed WMA songs. For DRMed songs to work they need to authenticate the user if the hardware is changed via DRM server. Walmart has sent email to its customers that starting October 9th it will transition to DRM free MP3 only and its servers will no longer support the DRMed music. 
In the email, Walmart has informed customers to burn the DRMed music files as music CD that they can use, if they change their computer. The email says that after 9th October you will be unable to transfer your songs to other computers or access your songs after changing or reinstalling your operating system or in the event of a system crash. In short, Walmart’s DRMed online music store is joining Yahoo Music and MSN Music. So, if you are one of the few Walmart online music store customers better write audio CDs, if you want to continue using your purchased music.