Thanks
I forgot to mention, I've already tried Audacity and Ardour (spelling?). Audacity crashes every time I try to run the Noise Reduction plug-in (apparently it's a bug:
http://www.mail-archive.com/debian-m.../msg02089.html). And Ardour, well, it's a bit too complex for me, so I have no idea where I am supposed look for a noise removal tool :P
Nonetheless, thank you very much for your suggestion, camorri