Some files are irreplaceable - family photos and tax records - which is why you need to take extra precautions when making backups.
The best way to protect your precious data is with offsite backup, and that's where broadband lets you take advantage of Internet-based storage and sync services such as Jungle Disk and DropBox
Jungle Disk works with Windows, Mac and Linux - letting you install a desktop client that runs in the background on your computer. You tell it which folders to watch and, whenever a file is added or changed, a copy is uploaded to either Rackspace or Amazon's S3 service. Jungle Disk starts from US$2 per month, with the first 5GB free and additonal storage 10c/GB per month. You can set how often to back up, how many previous versions to keep and throttle the upload speed so as not to choke your internet connection.
Rather than paying for each computer, Jungle Disk lets all your computers share the one online storage space. Jungle Disk also lets you access your files from any computer via a browser. There's now an iPhone app for remote access to your Jungle Disk storage space, plus it works with GoodReader on the iPhone/iPad.
Dropbox works in a similar way to Jungle Disk, keeping folders in sync across multiple computers (Mac, Windows, Linux). You can also access your files via a browser or from a smartphone (including an iPhone/iPad app, as well as access via GoodReader). Dropbox also lets you share folders and files online with family and friends plus create online photo galleries.