The VG Resource

Does anybody know how to get into a .dsp file. The file is from wario world.

Have you tried BRRESViewer? It can look at most model types used in Gamecube and Wii games. I can't guarantee that it will work with Wario World's file system though, but it's worth a try.

EDIT: When looking up how to convert an .aax file, I stumbled across this little app, and apparently .dsp files are actually the sound files that Gamecube games use. So what you have there is a sound file, not a model file.