I compose music with my computer, with a program named Impulse Tracker to be exact. Or, more accurately, used to. Now I use Schism Tracker. It's a pretty good clone of IT, but there are still notable differences. Well, notable to me, at least. I did use IT for closer to five years.
I mostly use ripped samples, but I have made a couple of guitar samplepacks myself. If you want those, you'll have to email me. Most of the songs are metal, ranging from power metal to viking metal to black metal to death metal, but there are also a few orchestral pieces and even one jazz song :).
I listen to most metals and some heavier rock. The metals I can digest include, but are not limited to; black, death, goth, doom, heavy, folk, viking, industrial and some grind.
I don't listen to rock much, mostly just some bands I've bumped into, like CMX, YUP, Babylon Whores, Kuollut Etana, some Apulanta and some others.
I also listen to some electronic music occasionally (mostly the "evil"-sounding stuff). I have a weakness for any genre starting with "Dark" :).
Real-time information of the music I'm listening can be found on last.fm.
On Windows, Winamp should play the songs okay, though if you have a very old version, or one of the newer ones, it might play them wrong. If you want more accurate playback, I recommend either XMPlay (this is required if you want to listen to the one in MO3-format) or ModPlug Player.
On Linux, both (x)xmp and anything using libmikmod do a decent job fucking up Impulse Tracker modules. Schism Tracker plays them pretty well, but as it's a tracker, it's not well suited for just listening to stuff.