You could even block instant messaging and email from anyone who isn't a fellow AOL user. Other tools available online operate similar to the way that AOL's Parental Control settings work, however no collection of tools could replace the reinforcement of mom and dad. Never let your children speak with strangers and never leave them alone at the computer unattended. You may find yourself in need of more hard drive space for all those videos and mp3s that you download, for example. Or maybe that cool new programming language you've been dying to try requires more memory than what your computer currently has. Unless the activities on your computer are restricted to pure textual output (plain text files), your computer is going to get filled with a lot of "stuff" - stuff that can overfill a PC's capacity too much for the computer to function well. But before you can see file extensions, you need to turn them on. From Windows Explorer, click on the "Tools" menu, and select "File Options." Click the "View" tab and then uncheck the box next to "Hide file extensions for known file types." Click "OK" and you'll notice that the files in Windows Explorer show a dot and group of three letters after their names. 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. In most cases, you can double click a file inside this window to use it, or you can select it and drag the file to a folder to view later. Depending on how you elected to install Winzip or StuffIt, you may be able to right-click a .zip or .sit file and have the program extract its contents into a new folder for you. Those who've purchased and used a computer in the past already have an idea of what they need in a new computer. But those who are new to the computer world could get lost in the myriad of choices available. The short answer to "What should I buy?" is "The best." Of course that answer is extremely subjective because "the best" to one person is certainly different to another.