We all know how important it is to back up files. If you don't know that, as a writer, you will at some point learn a painful lesson that drives home how important it is to constantly back up your work--just in case. However, something we don't always think about is having a backup to our computer. I have a laptop that I work all the time on. I confess that I no longer go for the most expensive, top of the line computers regardless of the style I choose. Things change so fast, and upgrading is easier if you buy cheap laptops.
Make sure you get one with enough power to do what you need, and that's enough. If you do go for a big, powerful and expensive computer, having a backup is still important. Too much can happen, and when it does, it happens fast. Anyone who has ever "refurbished" a computer that had a virus knows that it will never again be as good as it was when it was new. I've had several wiped and they never were as good. A few have been almost as good. I still always have a cheap backup. Even if you send your "good" computer (or your main computer, even if it is just a cheapie) in to be cleaned, you're going to be without the ability to work unless you have a backup.