Recently, A friend of mine was locked out of his Windows laptop due to a certain virus. While I have always found that the best anti-virus solution has been Microsoft Security Essentials, we are talking about the "cure" here rather than "prevention". I knew what was in store - I had to use a rescue disk and check the drive. And then (possibly) perform a repair of the Windows installation. If the above two processes didn't work, I would have to use a Live CD to extract the important data and then format the HDD. The problem - I had only one USB drive! If I had to go through all of these steps, I would waste a tremendous amount of time just making different disks. Not to mention, I would require access to a running computer throughout.
Enter YUMI.With this brilliant tool, you can install multiple distributions on your USB drive. Moreover, it supports a huge list of anti-virus tools and system tools apart from the popular Windows and Linux distributions. It is extremely use this tool in Windows and it can run (without the format drive feature) in Linux through Wine. A detailed documentation along with a list of known issues has been provided on their web page. Of course, a large USB disk is also required. I would suggest keeping at least the following on your All-in-One Boot Disk:
1. Operating System
Because I have a dual boot on my laptop with Windows 7 and Ubuntu 12.04, I have kept copies of both of these. The advantage of keeping Ubuntu is that it comes with a Live CD that will help you recover data in case of a major Windows meltdown. If you do not have any version of Linux installed and do not have enough space for Ubuntu on your USB disk, you can make use of the extremely small Linux distributions like Damn Small Linux (~50 MB) or TinyCore (~12 MB).
2. Antivirus Tools
These are a must-have because of all the vulnerabilities your Windows is prone to. Even with a fully functional antivirus on your computer, the importance of a rescue disk cannot be emphasized enough. For this the ISOs offered by Kaspersky, AVIRA and BitDefender are good options. Some people have complained about problems with using Kaspersky's Rescue Disk, though.
3. System Tools
These are good to have in case you want to partition hard disks, diagnose for certain hardware failures or to simply crack your computer's password for the forgetful ones. There are a lot of tools available for this purpose, the most popular ones being GParted, Ultimate Boot CD and OPhcrack. The number of tools offered for this purpose is so vast that it could be a separate blog post in itself.
There is also an ISO available called Hiren's Boot CD. It has a lot of tools included onto a Windows XP boot disk. Even though there have been certain references to it being illegal, I will not recommended it for completely different reasons. In my experience, this particular ISO comes with so many needless tools that it actually makes the recovery process more painful than a plain format and reinstall. Use this only if you don't have any clue about what is wrong with your computer.
1. Always have an anti-virus installed on your Windows PC
2. Always keep a regular backup of your important data, either on an external drive or using a service like Dropbox/Ubuntu One/Google Drive
3. Always keep your OS partition separate from your data partition
4. An all-in-one USB disk makes a quick-fix repair easy and painless