this will show you EXACTLY how to install rockbox on your flavor of h10 (20GB model or 5/6GB model)
http://www.rockbox.org/twiki/bin/view/Main/IriverH10Portalso, rockbox allows using winamp playlist, but you have to make them absolute.
meaning if you have a playlist that points to D:\music\artist\wah.mp3 ;
you have to remove the D:\ part.
the best way to do this is with wordpad or any other favorite txt editor.
just open your .m3u (winamp playlist) in there and tell it to replace all occurrences of whats not needed with a nothing.
for instance, i have all my my music on my pc in this format
D:\music
..............\artist
........................\album\blah.mp3
........................\album 2\wahmp3
so most of my playlists are stored in my main MUSIC (d:\music\)
so they all point an artists folder already.
in rockbox on my h10 i have a folder called music (make sure you UNHIDE this folder as it is hidden in windows by default and rockbox wont see it)
so my m3u playlists look like D:\music\artist\album\wah.mp3 and so on. i delete everything trailing the artist so it now looks like \artist\album\wah.mp3
it's pretty easy, but the explaination is long.