The best way to back up your PC is to the cloud -- that way you always have a secure backup away from your home or office. There are plenty of them out there -- here are my five favorites.
If you're looking for value and simplicity, Backblaze can't be beat. You get unlimited storage for a single PC or Mac for $50 per year. No need to select folders and files to back up; Backblaze does all that for you, and then begins backing up right away. It backs up continually as you work, so if you crash, you'll have pretty much the latest versions of your files online. There's also a Web interface for seeing your backed-up files, and apps for both iOS and Android. When it's time to restore, you can choose only certain files and folders, or else restore them all. One nice extra: It give you a report of what types of file have been backed up --- documents, photos, music, financial information, and so on.
If you have multiple PCs, Macs, Phones, iPads, and Android devices, this is a great service. For $45 a year, you can back them all up. You get 1 terabyte of total storage space for all devices, combined. Like Backblaze, it offers continuous backup. There's a Web interface and mobile apps as well. If you want to back up more than one device, and won't exceed 1 terabyte of data, it's a great choice.
Here's another very good service. For up to five PCs, and iOS and Android devices you get unlimited storage, for $70 per year. Not only does it let you back up to the cloud, but you can also back up to a hard disk, network-attached storage, and CD/DVD/Blue-ray. There is a drawback, though -- it doesn't work with Macs.
Carbonite is one of the best-know backup services, and it's a solid choice. You get unlimited storage for $60 per year for a single computer for either Windows or Mac. It's extremely easy to set up and use, gives you control over when and how to back up, and has a Web interface and apps for iOS and Android.
CrashPlan backs up Windows, Macs, and Linux machines and give you unlimited storage for $60 per year. There's also a family plan for multiple devices. It backs up continually, and gives you easy control over what to back up and restore. And there's a Web interface as well as mobile apps. You can also back up to other computers, not just the cloud.