Well, don't get me wrong, this isn't impossible to fix. But in order to do so, I think you'd probably have to spend quite a bit of time learning the many facets of humanization that you could probably learn more easily by just making more music in the meantime. I think your time would be better spent coming back to this later, but that's 100% my opinion.
I do have to change something though, since I've used EDIROL Orchestral and the samples are actually quite nice. I'm not sure why they're sounding so stiff and unrealistic in this song, maybe it's just an illusion caused by the unrealistic sequencing, as well as the attack and decay values like Stevo is saying. I know for a fact that you can get great sounds out of the VST you're using, actually.
I realize my last post was kind of discouraging, but I hope you don't take it to mean that it's impossible to get this up to workable standards. I was just giving my personal advice on how I feel is the best way to improve your craft, based on what I've seen from other people burning out when they dwell on a song for too long. Your mileage may vary.