Now that you've created a system-repair disc, dumped the junkware, and taken steps to secure your new PC, it's time to perform what I consider to be the ultimate hassle-prevention step: imaging (a.k.a. cloning your hard drive).
See, right now your system is exactly the way you want it. You've got a fresh install of Windows (one that's newly free of crapware), the latest versions of your favorite apps (which I'm assuming you've already loaded), and all the security tools you need.
Wouldn't it be great to take a "snapshot" of this setup that you can restore in the event of catastrophe (or merely the inevitable slowing of Windows over time)? That's the idea behind creating a drive image: It can restore your PC to a like-new but custom-configured state.
In theory, you'll need to do this just once (unlike regular backups, which you should perform daily or weekly). And you may never actually need the image file--but if you do, you'll be awfully glad you have it.
There are countless programs that can clone (and restore) your hard drive. For my money, it's hard to beat Macrium Reflect Free. As the name implies, it's a freeware tool--but don't think it's any less capable than various commercial programs. In fact, PC World's Jon Jacobi says "its interface is the friendliest I've run across." (I'm sold.)
So, where you should store your cloned hard drive files? Macrium gives you a choice between DVDs, external drives, and even network drives. (Personally, I say buy an inexpensive external hard drive to use for this and other backup purposes, but to each his own.)
If there's another clone tool you'd recommend for this procedure, feel free to mention it in the comments. In the meantime, I can't recommend this step highly enough. It's well worth a little bit of your time.