(The software linked to does) ... not to load new sounds.
Ha. I see, just control the unit and create "macros" to do a set of actions. I see. All the way to (it sounds like) recording a drum performance and playing it back.
An open source drum machine would be great, I have no clue how to build one, nor do I have the money at this time.
Knowing about building hardware will obviously be a prerequisite. That's the bad. The good is that I can't imagine it costing anywhere near what a DM10 would cost. Maybe because I don't know all the things a DM10 can do. The other good thing is, as with most opensource projects, is that the software could be (mostly) done by others (and/or by you if you figure out hit bits and pieces).
No clue about Linux and Ardour.
I picked Ardour because it is Linux centric. I have no idea how it stacks up with commercial or other open source efforts.
A Linux Live disk is a general term used to describe a CDROM or DVDROM which can be used to bring up a Linux system on most commonly configured Personal Computers. The part people have a hard time understanding about a Linux Live disk is that it does not matter what in running on the computer. It does not matter what software is on that computer's hard drive. And after running a Linux Live disk the computer is expected to be unchanged upon the next boot up after the CDROM or DVDROM is removed.
People usually make Linux Live disks because they don't want to install Linux but only take it for a test drive. The other reason people make Linux Live disks is to run a Linux application. See, you can configure the Linux Live disk to simply boot up a Personal Computer and run the Ardour application automatically (effortlessly).
Also I have never heard of Hydrogen, I will look into it.
Hydrogen is Linux centric. So support is better for Linux. I see they have a stable release for Linux but only a snapshot of the newer unstable release for Windows. Hum, I also see where you can download "sound files"! Interesting!.