I'm planning a vacation and have a fairly new Nikon Coolpix 5900 camera; I have one extra memory card (and might get another before I go), but was looking for a spare battery. Is it necessary, in your experience, to purchase only the branded Nikon battery? I've seen "generic" ones, notably on the Duracell website, significantly less expensive. I don't want to mess up while I'm away, but if I don't HAVE to get the branded one, I won't.
Thanks for the info.

You don't need to get the branded one.

No need to buy the branded battery; just make sure you take your battery charger and keep a charged battery handy for when the first one goes. And recharge that first one as soon as you get back to your hotel room.

I always use either Memorex or Duracell for my Nikon Coolpix 3100.

Thank you all! I just ordered from Amazon.com, and will take the charger also. I doubt I'll go through two whole charged batteries in 10 days, but will recharge each evening, just to be safe.
Thanks again.

What I did was order a charger that runs off 12V and buy a separate 12V Switched Mode power supply.

It means that I can run the charger in the car or off any mains voltage.

Did exactly the same with the charger for the AA batteries - means I only have to carry one mains power supply around the world

I also use generic batteries in my cameras and have never had a problem. However, you should know that if anything does go wrong, most camera warranties won't cover you if you were using a non-branded battery.