Hey man.
I noticed you change the tempo throughout the song when the vocals come in.
I know exactly how to fix it, and it'll really make this song sound so much better.
I'm serious, it's one of the best methods when remixing songs with acapellas. You can sync an acapella and play it at any tempo, at the same pitch and still in sync to the beat. Since I'm about to go to sleep, I can't lead you through it in msn or pm's so I'll tell you to follow this tutorial. It's great.
http://www.youtube.com/watch?v=f7Z51G pr3zg
Also the tune you used is much like Take a Look by Nate but it doesn't matter. Just wanted to tell ya.
5'd
Keep up the good work! :D
-Cheers Brando