dBpower AMP can still be obtained in several free versions. It is a music file format converter. click here for v10.
Go to Codec Central click here and download/ install the .wma codec. This codec is not preinstalled in dBpowerAMP.
Provided that the .wma files that you are trying to convert are not copy protected...you should be ok.
If you want any more help on this, just post back.