The developers of Schism Tracker are doing a very great job! Last time I could test a CVS build, it couldn't load most of the XM files properly, browsing samples was almost impossible, there was no good support for instruments... and now everything is fixed!!
They also have added suport for resizing the window (they do not control the aspect ratio so you can make the fonts as wide as you want... it's funny!), and even more: now you can write a WAV output directly from Schism Tracker.
There are still some bugs here and there but this is very very usable right now. Thanks once again to the developers :-)