Good work on this. :)
You did a good job at orchestrating the strings part, but you could have added more percussion to this- anvil, a bass drum at fortississimo to make it pop, crash cymbal at the start of each pattern, etc. In addition, you could have easily lengthened the piece with a simple B melody following the great beat you had going! Until you get a new computer and/or get your setup fixed up, best of luck on your other projects.
The piece is overall rather quiet. Consider looking at the mixing/mastering styles of Cinematic works as a basis for that "pop" that is there in action scores.