Reformatting and restoring a PC is not fun, in the way spending 2 hours in the dentist's chair is not fun. You have to back up all your data (and pray that you haven't forgotten anything), reformat the hard drive, install Windows, track down missing drivers, find and reload all your software, restore your data, and pull out clumps of hair over the things you inevitably neglected to save. (Firefox plug-ins, anyone?)
Definitely not fun, yet it's something that most PC users end up doing at least once. When your machine becomes so sluggish, flaky, malware-infested, or ill-behaved that no optimization utility can help, sometimes the only remedy is a full system-wipe and restore.
If you're smart, however, you'll look upon this as an opportunity, not only to return your PC to its former out-of-the-box glory but also to make it better than it was before. I'm talking about implementing a bulletproof backup system to thwart future disasters, organizing your folders and desktop to keep clutter at bay, cutting performance-clogging security software to a bare minimum and making sure that if you ever need to reformat and restore again, the process will go a lot easier.
In other words, you've cleaned house. And now it's time to get that house in order.
Create an image of your newly restored system
Windows installed, updated, and personalised to your liking? Check. Important apps loaded? Check. Drivers working? Check. Now step back and bask in the glow of your perfectly configured, smoothly running PC. Don't you wish you could capture this moment forever, and even preserve it for the future in case something goes awry?
You can, by creating an "image" of your system as it exists right now. An image is essentially a full-system backup, but one that contains all the extra stuff that gets added after a fresh Windows install. By making that image your go-to restore source, you can save a ton of time if you ever need to do another system overhaul. (Remember, however, that an image isn't intended to preserve your data; that's an entirely different kind of backup.)
Countless drive-image utilities are out there, but I'm partial to Macrium Reflect Free. It's easy to use, and it can save your image file to an external drive, a network drive, or even CDs/DVDs. It'll also build a bootable rescue disc for restoring the image, just in case you're trying to resurrect a seriously compromised system.
Add a Linux partition
Admit it: You've always wanted to try Linux. It's a fast, robust operating system, stocked with all the software that most users need for everyday computing. Plus, it's free and if your Windows install ever becomes too messed up to boot, you might be able to use your Linux install to save it.
This is the perfect time to create a dual-boot environment, to devote a chunk of your hard drive (a partition) to Linux. When you're finished, you'll be able to choose Windows or Linux every time you boot; it's like turning one PC into two. And in the unlikely event something goes wrong during setup, no major harm done: You could just whip out the drive image you created earlier and restore the system to its previous pristine state.
I recommend the Ubuntu version of Linux, though you can find countless others to choose from. To install Ubuntu alongside Windows, you'll need to download the OS, burn it to a CD, create a partition within Windows, and then boot the Ubuntu CD and follow the instructions. Ubuntu's own Windows dual-boot help page spells all of this out in much greater detail.