Yamaha DTXpress/DTXplorer/DTXtreme

I've had a dtxpress for 2-3 years now, I use it regularly with a band.
We are recording at the moment, I record drum tracks staight onto the 
dtexpress, then via audio leads to an 8-track. I have run out of 
memory for storing more songs.

I would like to know (in simple terms) how to send only drum tracks 
and kits onto a PC and be able to send them back again. I want to use 
the HOST connection (to PC serial port). 

Can I use windows hyperterminal to do the above?
If so, what settings (BAUD, parity, etc..)?
What file format will the files arrive as?
Can the above be achieved without having to mess with MIDI?

I have recieved something (3kb file for one song) but I can't send it 
back again.

Can anyone help? Please??

Fancha.