Being aware of or deciding who else should have access to your computer is a much larger security concern than whether or not to use a desktop search tool. Anyone with physical access to the machine can find the same information as the desktop search tool can given the desire, some time and a little bit of knowledge. In other words, a desktop search utility might greatly expedite someone finding information they shouldn’t have access to, but not having a desktop search tool will not completely prevent someone from finding such information. It just means they will have to hunt and peck and search through the files the old-fashioned way.
Where a tool like this becomes more of a security concern is on truly public computers. Computers at libraries, schools, Internet cafes and other such establishments have random users coming and going all the time. Often, these users log on for the sole purpose of checking web-based email or verifying their account balances on credit cards or at their bank. Having a utility like X1 or the Google Desktop Search tool installed on a computer like this would make it very easy for a user to do a search and retrieve information from past user’s sessions.
Again though, the burden lies with the provider of the public computer to ensure some level of safety or security to protect the users as well as with the users themselves to exercise the appropriate level of caution when entering private and personal information on an insecure public computer. While public access computers have even more reason not to install a desktop search tool than say a home computer, the fact remains that any user with physical access to the machine can gain access to the same information given the time and desire.
The administrators of public access computers should have some means in place of ensuring that the temporary internet files and other cached information are purged between user sessions to ensure this sort of information does not linger from one user to the next. When you are using a public computer you may want to look for the colored swirly logo in the systray that indicates the Google Desktop Search tool is installed or check the Add and Remove Programs in Control Panel to verify that no such tool is installed before deciding to enter your private information on the computer.
I highly recommend X1 or the Google Desktop Search tool for any user who is the sole user of their computer. They are invaluable tools and make finding the information you have stored on your computer exceptionally more efficient. Should your computer ever be lost or stolen such a tool will make it easier to sift through and find your personal information, but, to beat a dead horse, if they have physical possession of your computer they can get that information anyway.