Thanks for these suggestions
I often used Pro Tools Free and Audacity under Windows
Pro Tools Free : unfortunately, only for Windows 98 / Me (!) -- should work under XP in Compatibility mode though Under W98, it crashed a lot when I used it, maybe it is rather suited to Apple computers ?
Audacity : this one is getting better and better, but there is still no dynamic trimming of the beginning and ending of the waveform regions ... (or else how do you do ?)
Ardours looks like being the best free multitrack DAW program ; I will use it under Linux ... when my sound card is compatible again (hdsp) ! If anyone knows a similar program for WinXP, this information is welcome.
have a nice day,
J