Hold the can perfectly vertical and spray the fan being careful not to spray the dust off the fan onto other sensitive parts of the computer like circuit boards or inside the motor casing. Wipe up remaining dust with your anti-static rag and then reassemble the computer. One thing that you certainly don't want to use to remove computer dust is a vacuum cleaner. Both files are capable of opening plain text, however WordPad can open Windows Write files (an earlier version of WordPad) as well as rich text files. WordPad can also save documents as plain text, rich text, and MS Word documents. So with WordPad having the ability to read and create rich text; embed objects (sound, pictures, and video); and manipulate fonts, we have to wonder if other word processors, which do the same thing, are really necessary. This way, personal data (such as bank statements, store receipts, health records, etc.) is protected from prying viruses or hackers, while the newer machine is used to surf the net. As you can see, old computers still serve a purpose either for you or for someone else. And although selling an old computer is always an option, there are a number of things that you can do with an old computer. Conditions allow a program to perform an action based on the outcome of a previous command.3 Using this type of instruction, we could instruct a program to do one thing if the "x" variable in our latter example turned out to be 7 days, and then do different thing if the variable turned out to be 3 days. Decompressing Files Assuming that you have Winzip or StuffIt installed on your computer, you can access the files archived inside a .zip or .sit file by simply double-clicking the archive (a file ending in a .zip or .sit extension). Double-clicking one of these kinds of files will open up a window that displays the contents of the archive. Some of the more popular ones are Windows Vista, Mac OS X, ZETA, IBM, Unix, and Linux. But even still, operating systems have extended onto to non-computer devices such as game consoles, portable music players, and PDAs. Regardless of the device, the operating system installed onto it serves the same purpose across the board: to enable user-to-hardware communication.