That sounds like it could be the start of one MASSIVE song....although the style's completely different I'm thinking of something along the lines of Dream Theater's 'Six Degrees of Inner Turbulance' where there's an orchestral-based 'overture' as the first part and then you get the six songs which all contain some of the ideas from the introductory overture. Symphony X's 'Odyssea' is a bit like that as well....there's a band who could have conceivably come up with an intro like yours.

I guess that answer's the question, yeah I think it's good enough to be on a professional full length album, although you might want to tweak the mix a little as the violins sound a little too loud over the horn section towards the end. I really like the way it starts, I've always like the horn's epic-sounding qualities.