Pretty good. And for goodness sake, have some confidence in yourself! Great music has been made on age-old pc's. I used to use a Pentium 100 and got 16 tracks of decent audio from a Soundblaster Live card!! It's what you do with it that counts!! Which is why your attempt is good.
My gripe with this kind of thing is the DI'd sound and the way you've cut off the end parts one by one, rather than simply fading each line out together. One of the important parts of Brian's sound is a mic'd up deacy. The difference is very important once you hear someone who has mic'd up and got things sounding right. That's one of the important parts of these orchestrations.
My advice is to try miking it up and maybe trying that. Or even What John's suggesting, if you want.