Find someone with a Creative Labs Audigy sound card. On the installation disk is a program called Creative Wave Studio which allows you import/change/export etc WAV and MP3s (and .RAW files). You can import as a WAV and export as an MP3 and vice versa so it is very useful. You can also get to do lots of stuff with the actual waveform so chopping or cropping is not a problem.
Anyway, I'll do it for you by email if you like, just let me know via PM.