I would propose the "self insurance approach", i.e. if your laptop would totally break, you would just buy a new one wherever you happen to be. Unless you're in the "middle of the jungle", there are going to be many PC shops around. It won't cost much for a basic PC laptop, and you can keep going after a short break to install the new machine.

This will get you back to speed in after about day or so of delay. Then you need a solution for surviving if your laptop breaks just before an important meeting or something:

For the really top critical things, I do carry backup hardware, for me this is a) Ability to show my work presentations, b) work email and VPN intranet access and c) secure passwords access.

I use my iPhone as backup, which I carry anyway.

Both PowerPoint and Keynote presentation apps work well on the iPhone, you can present well to projectors or any TV using the VGA and HDMI dongles or even make some last minute edits to the presentation.

So the only extra I need to carry are the iPhone VGA and HDMI dongles, which are small and light.

Before each trip I sync over the presentation files from my laptop to the iPhone (I use the GoodReader App to manage files on the iPhone), along with PDF travel itinerary and other files I might need.

This means that if there would be a major problem with my laptop, I'll be able to go on and do the most critical things during the trip with the iPhone, not perfectly, but OK, and keep goinggood enough until getting back home.

I've had some hardware failures during my trips, but I've been able to buy the necessary new power supplies, cables, hubs, etc. while going on with the stuff on the phone.