Hi -- please can you give some more information about what version of SV you have, on which platform, and where you got it from?
For example, if it's a Linux version -- as your username might suggest -- did it come from this site (via SourceForge's download page), or from a distro package (and if so, which), or did you build it yourself?
SV does include mp3 support, but only if it has been compiled with the appropriate mp3 library and options. All of the binaries from this site have been compiled with mp3 support except, I think, the Windows build of SV 1.0. The forthcoming 1.2 and its prereleases should have mp3 support on all platforms.
Chris