Thank y'all for the reply, and thank you very much mylemonblue, for the extensive advices -- they're all helpful to me.

My laptop (bought in 2004) doesn't support USB 2.0 even though the manufacturer said otherwise, and most of the external hard-drives (mostly with USB 2.0) in the market don't work with my laptop. 

I'm planning to buy a desktop PC in the near future with big space, and an external HD to accommondate both P5 and P6.  But for now, I think I'll just stick with P6 while using all the tips you gave.

Thanks again!

BEST!