There are a couple of ways to backup your computer. You could perform regular backups of your important files and data so that you can restore them if your goes kaput and you have to build a new system or reinstall the operating system and programs from scratch. Or you can create a complete disk image that you can use to restore your computer to exactly the state it was in the moment you created the backup.
While there are plenty of free utilities for performing both types of backup, most free disk imaging software requires you to reboot your computer and load Linux or simplified version of Windows to complete the image. That means you can't create your backup while you're using your PC to do other things. But
Macrium Reflect Free Edition lets you create an image of your Windows system while using Windows.
Macrium Reflect comes in 32 bit and 64 bit versions and is compatible with Windows XP and Vista. You can image a complete disk or just individual partitions. And you can save your images to a local hard drive, network drive, or optical disc. You can also schedule backups and create restore discs using Linux or BartPE.
We were able to backup a partition with 12GB of data in just about 16 minutes. Since Macrium Reflect lets you create compressed backups, the image weighed in at just 8GB.
There are some features that you can only access by paying $40 for a fully licensed copy of Macrium Reflect, including Windows Server 2003 compatibility, differential and incremental backups, and the abililty to backup and restore individual files and folders. But the free edition is still pretty useful and provides an easy to use alternative to previously mentioned
DriveImage XML.