Apple Logic Pro /LogicExpress Discussion

I've made loads of progress recently, with thanks to all the experts  
here for sharing their knowledge, so I thought I'd pass on something  
which might be of use!

I'm writing a dance song for a music competition, and I wanted a  
pumping sound in the pad. I found this tutorial on youtube, which just  
happens to be by the Freemasons demonstrating how they put together  
'Uninvited' (which also happens to be my favourite song of the  
decade). I found it incredibly useful

http://www.youtube.com/watch?v=lxeBrJP52vY

I had my song set up, and I was using an older version of it as a  
guide, which I loaded up as an audio file. It was at 144bpm and I  
wanted the song to be slower - 138bpm. I put the parts of the song in  
whilst working at 144 and when I had it all in place I deleted the  
audio files.

I copied a drum kick to an audio file to use as the sidechain input  
for the pumping pad, and spent ages making sure that the pumping sound  
was totally in time with the beat. Actually, I couldn't tell the  
difference between the release that I chose and the automatic one.

Happy with what I'd done, I listened to the whole track and found that  
the pumping was totally out of synch, which I couldn't understand.

In the end I worked out what was wrong - I had made the audio file for  
the kick at 144bpm and was playing it at 138bpm. I made another audio  
file at the right speed. Problem solved!

Does anyone have any other tips on this subject? The Freemasons seem  
to put the sidechain in loads of different tracks, but for me this  
makes the song sound wierd. Should I use it for bass? Vocals?

Andy B