Start > Type "Backup" choose Back up your computer
On the left side of the window, click Create a system image.
This will create a system image that backs up, not only your personal files, but the operating system as well. It creates a snapshot of your hard drive and everything installed on it. You'll need to back up to a storage device with enough capacity to cover everything that is currently installed on your hard drive.
In the same window, you'll also need to Create a system repair disc, so you can boot from it to load the system image that you create.
Windows 7 is pretty good about adapting to different hardware, if that's your plan. However, I know that *if* you are changing motherboards and go from Intel processor to an AMD or vice versa, the system image will NOT adapt to the hardware changes. Stay with the brand processor you currently have installed, and it *should* work. New hardware always means different drivers from the ones currently installed, but those should be supplied with the new MoBo. Don't expect everything to be 100% working afterwards, it will take some doing.
Because of the new CPU and MoBo, Windows will probably require to be re-registered with the COA (windows product key). You can retrieve this from your current windows installation by using magical jelly bean (link here:
http://www.tomshardware.com/answers/id-1819949/find-windows-product-key.html )
I suggest downloading and running Ccleaner (www.filehippo.com) before you create the system image. It will help clear a boatload of temp files and speed up the backup process.
Good Luck!