As the Wikipedia article explains
SyncToy is a free PowerToy designed by Microsoft that provides an easy to use graphical user interface that can automate synchronizing files and folders. It is written using Microsoft's .NET framework.
SyncToy can manage multiple sets of folders at the same time; it can combine files from two folders in one case, and mimic renames and deletes in another. SyncToy can keep track of renames to files and will make sure those changes get carried over to the synchronized folder.
It's been around for a while, but I've only recently started using it and it has completely eliminated the need for my old fashioned manual process, which started off as adequate but steadily grew to be a massive headache to carry out. The software is fast, intuitive, and does what it says on the box and it shouldn't take more than 15-30 minutes to install and set up backup folder 'pairs'. There's a bunch of fairly straightforward options that can be configured with ease, and it provides a useful preview button so that you can see what it's about to do (in case you're paranoid and worried that it'll overwrite your secret stash of whatever it is you're into). The actual backing up (or synchronising) is simply a matter of clicking one (or two, if you preview) button.
Important point to note. Backing stuff up onto the same hard disk is useful if you want to have older versions of your software available, but is useless for recovering your data if your computer gets screwed or the disk breaks down. I personally use a second hard disk to back stuff up, plus a USB flash drive for all the extra important stuff. Given the capacity and price of flash drives, that's probably the optimal solution, unless one is backing up gigabytes of data, like digital photos (which ought to be backed up to DVD or CD, really).
Anyway, my backup process has now been reduced to a few clicks once a week, and I'm a much happier chipmunk as a result. Synctoy is a godsend - this is one Microsoft product that I can wholeheartedly recommend! Although, if it somehow winds up eating my hard drive and destroying my data, there may be another blog post on this topic in the future!