If Dropbox, Google Drive, Microsoft Skydrive and all the other such systems still haven't tempted you with their free service, and you are still looking for a source of online storage space for files and backups, here's news of yet another provider.
Amazon has something called Amazon Cloud Drive. Like all the others, it's free. Unlike Dropbox, which offers just 2 GB for free, Amazon gives you 5 GB of space. Plenty to store your important documents, files and so on.
If you already have an Amazon account, activate your free Cloud Drive at www.amazon.com/clouddrive
There's also a desktop client application available, again free of charge. You can get both a PC and a Mac version, which can be downloaded from http://www.amazon.com/gp/drive/app-download. Unlike Dropbox and other such systems, however, the Amazon app doesn't create a synced folder on your desktop. Instead, it allows you to upload to your cloud drive by dragging files to a special area of the screen, in a similar way to that offered by some online photo sharing tools.
The desktop app for Windows is a 30 MB download, and according to Virus Total is free of malware. However, be aware that it doesn't run on Windows XP, and instead requires Vista, 7 or 8.