Tip: Take Windows back in time without System Restore
System Restore is good when you're in a tight spot, allowing you to roll back your computer's key programs and system files to earlier versions in an attempt to fix a problem. But it's not foolproof, and because it doesn't roll back everything, it can't be relied on to always solve your problems.
Comodo Time Machine offers a free, all-encompassing alternative: instead of just rolling back certain files, it allows you to roll back all the files on your Windows drive, sending you almost literally back in time to the point where your chosen snapshot was taken. It's not just good for fixing problems (and we include virus infections in that), it's also great for those who have to install lots of software on their PC for testing purposes, helping keep the PC running without the need for a regular Windows reinstall every six months or so.
Comodo Time Machine is a very powerful tool, and despite the relatively friendly user interface, can still cause problems if you don't know exactly how it works. First, it's best to use it on a multi-partitioned drive, which you'll need to do before installing the program as it doesn't work well with partitioning tools once it has been installed. Keep your data stored on a separate partition to Windows and your programs, so they're unaffected when rolling back your system, otherwise your data takes a trip back in time too.
Second, Comodo stores your system snapshots in your drive's free space, which means you'll need plenty of that (10GB minimum, 50GB recommended) handy. Also note that Windows is unaware of this arrangement, so don't rely on it to tell you how much free space is actually left going forward. Instead, keep an eye on what's happening within the program itself, and don't allow free space to fall too low or else Windows will start running into problems (thankfully you can access Comodo before booting into Windows to delete unused snapshots and recover free space if it becomes an issue).
You can store as many snapshots as you have space for -- and branch off different snapshots too, making it a really useful tool for those who'd like to experiment with multiple setups. Restoring previous snapshots is quick too -- much quicker than restoring a drive image, and you can configure the program to take a snapshot before you restore, in case you decide time travel isn't in your best interests this time after all.
Is Comodo Time Machine reliable? I've been using it now for the better part of a year, and it's saved me numerous reinstalls. I've encountered all of the teething problems above, so hopefully by following these tips you'll avoid the trouble I had, allowing you to take full advantage of its capabilities. But do take a full backup and drive image first, yes? You can never be too careful.