wow the file was sorta HUGE.
The tune was cool. Good work. I like the arrangement, and the idea is pretty cool. However, there's one thing which keeps this away from being an OCRemix : The samples and the production. The brasses are kinda OK (although ,you should work with dynamics and vibratos), but the drums, bass, ukelele-sorta-thing and piano sound like midis (good midis.. but still, midis).
From what i read, you use Fruity Loops (or FL studio), and your computer has 1 Gb Ram. Well, I work with the same program, and the same Ram. if it helps, there are many plugins which might help you : EWQL Stormdrum and EWQL Hardcore Bass are plugins i use a lot for bass and drums, they work nicely and smooth under FL Studio. Plus, Garritan Personal Orchestra has a really cool piano. You should check them out.