Depending on their binding legal agreements, licensing typically allows the use of a single program on a single computer. This set up is usually fine for a user who uses software at home on one computer. But in an environment where there are five, ten, twenty or more computers, buying a license for each computer can be down-right costly. Firewalls prevent - but they don't repair. Only anti-virus and anti-spyware programs can reverse damage. So you should install a firewall on the computer that grants access to the computer, and then install an anti-virus and anti-spyware program on each of the remaining computers in the network. If you have files that shouldn't be shared (bank statements, credit card information, etc. An Introduction to File Extensions In an effort to be "user-friendly," Windows (and perhaps some other operating systems) hides the most important part of a file name from new computer users: the extension. Okay - we're assuming that the reasoning behind hiding extensions is a "user-friendly" one because we just can't come up with any other reason for hiding them. You could end up typing a command as wide as your computer screen or worse, long enough that the entire command would have to wrap onto the next line! Now imagine having to type these long commands every time that you wanted to start a program. Yikes! That's one of the reasons why batch files became so popular. The only time that you wouldn't want to delete an orphan file is if the file were an actual document that you created before deleting a program. If you were to say, uninstall Microsoft Word, all the documents that you created with Word would then turn into orphan files. Or if you were to uninstall a graphics-editing program, all the pictures you made with the program would become orphan files. exe extension, take note that although the file is compressed, it's typically a file that will install a program onto a computer. .Zip or .Sit files don't install software - they merely archive a collection of them into one, or they significantly reduce the size of a larger one. Decompressing Files Assuming that you have Winzip or StuffIt installed on your computer, you can access the files archived inside a .