portable / external hard drives on a Mac

Hi, I just ordered my first mac today, the new macbook white. I want to just keep programs on the internal drive and have two external drives for the same file storage, one backing up the other. I already have a portable 160gb.

So in that case I want to leave the drives connected all the time while im at home atleast. My question is will the portable drives damage the power supply even if the mac book is plugged in? Should I get external drives with their own power supply instead to be safe, or am I over reacting? Thanks, I look forward to switching to mac.

I think you are being overly cautious.

I hope so but I don't like suprises.

You're being to cautious. I do my own radio show through LiveVideo, and I run the two drives, and it's s'all good.