ok. I need help with basic design.

I'm trying to make battery pack for my PDA
I have 4 1.2v 1200mAh battery
I was wondering if I can just connect a plug wire to each end? or do I need diode between wires?

and I'm also try to have dpdt siwtch for power to pda and recharge the battery pack can some one help with design.

Thanks for your time