That Garage band thing sounds great to me. Is it versitile enough for you to programme what you want the Drums to do [ like a drum machine ] & Bass ? & can you get it to do keyboard sounds ?
GarageBand comes free with Apple machines (
http://www.apple.com/ilife/garageband/), I believe. If for some reason you didn't have it preinstalled, GB is part of the iLife app bundle which retails for USD 50 or something. No Windows version (not surprisingly).
GB is
excellent for quickly sketching out song ideas and rough demos -- probably not powerful enough for pro use (for which one would move up to Logic, which is pro) but I don't know enough about audio engineering to make anything pro anyway :). It's basically a hyper-friendly DAW interface, doing multitrack audio/MIDI recording with a bunch of basic presets for real instruments and vox, a host of "software instruments" (like soundfonts, basically), and a big raft of loops. You can buy Apple or 3rd party add-ons to increase your options in these various categories.
GB's amp sims are a bit of a weak point. There are some all-rightish presets and you can futz with the settings, but there's only so much to work with. GB isn't really intended as a guitarist's toolkit, though, so one just has to find one's own solutions there.
You could, in theory, program your own custom MIDI drum parts right in GarageBand, though I think this would be a tedious pain in the @r$e :) Easier to just use some basic drum loops when sketching things out; you can always program your own custom thing in something like Doggiebox later and import the audio files to GB (there's another app called iDrum that's supposed to integrate with GB in some way, but I haven't tried it).
I've got a bunch of half-arsed demos on my personal web site, some of which I've recorded recently using the quick-n-dirty technique of slapping down some drum loops and accepting the presets. This is plenty good enough to get a song sketched out for one's bandmate's to learn from, though I'd need to program the drums properly and sort out the guitar amp/amp-sim situation (to start with!) for anything more polished.
Now that I've finished wibbling about GB ... nice track! Would you be willing to divulge more of your GB amp settings? :) I've kind of come to accept that they won't do in the long run, but in the meantime I've been pushing the settings and FX around on them in an effort to get something better out of them.