Windows 7 comes with a backup/restore program that you can use. The most attractive benefit to using it is that it's part of the Windows installation disk - and restoration is one of the advanced options. Best way to use it is with a big external drive. It can also backup the whole system image - meaning the partition and format is backed up too. Another nice thing about it is that any installation disk will work. So you could download and burn any W7 installation disk and it will work without having to look up your license.
However, Macrium Reflect also has an option to make a bootable emergency disk. Not sure if it's available in the free version or not. But if it is, Macrium Reflect is an excellent alternative with more available options.
I noticed that nobody ever recommends Norton Ghost anymore. Norton created a wonderful standalone backup program and then they destroyed it by bloating it into an unwieldy enterprise only behemoth.