Here is something I did very quickly, i got a huge inspiration from some songs (mostly this one http://www.youtube.com/watch?v=rxqENoZ5IOs&list=FLVabQShN2aElId46vYGuzrg&feature=mh_lolz ) and i just composed this in "oneshot", which is something quite unusual for me...

Definitely sounds like some serious film soundtrack (it makes me think of Matrix...), though the calm part can sound pretty weird.
I really like the guitar riff, but i'd like to know what is your opinion on the scale change i have done... Does it sound ok ? I sometimes think that I should make the calm part longer to make the transition sound less "precipitated" (wtf)

Anyway, here it is.
Compo 118.gp5
It all sounds OK to me. More than that, it sounds pretty epic! Nice riffs, and a melodic interlude at 26-42 is awesome.
I started this thinking I was about to hear the generic Hans Zimmer rippoff sound that is now known as "trailer music", but as soon as the guitars came in I was wrong. The song is full of life and dynamics, and the key changes are all smooth, and the combinations of instruments all make for good colors. My only suggestion would be when that main guitar riff comes back at the end, I would either make one guitar play a higher harmony at some point, or introduce another instrument for counterpoint with it (well, there's technically already counterpoint, but I mean one that keeps the rhythmic features of the riff). I would keep in mind that making this sort of music depends nearly as much on production skills as composition skills, so I hope you can manage to make an excellent sounding recording of this.
I would even say that production skills are even more significant than the composition ones because you can do some epic soundtrack with a quite poor line.
I'll think about your advice, I may do something like this !

Thanks for those comments guys, I really appreciate it.