zip format (if you're using Windows) or .sit format (if you're using a Mac). The two most popular software programs used to compress and decompress files are Winzip and StuffIt respectively. There are other programs that do the same thing and there are even programs that can compress and decompress files for both the Windows and the Mac system. But you can prevent identity theft from occurring by installing a firewall. A firewall is software that checks all data entering and exiting a computer and it then blocks that which doesn't meet specified security criteria (user-defined rules).1 5. Don't click on website links in spam messages. In an effort to obtain personal information, some spammers will send email that asks you to click on a link. Since we're describing a home network that will connect to the Internet, you're strongly advised to install a protective firewall program to thwart Internet viruses, worms, or other damaging spyware code. Firewalls prevent - but they don't repair. Only anti-virus and anti-spyware programs can reverse damage. avi - This extension indicates a video file playable by most multimedia viewers including Microsoft's Media Player. .bmp - This extension indicates another image file that might have originated from Windows Paint program. .dll - This extension indicates a Dynamic Link Library which may contain additional programming code for software. For those entering the United States from a foreign country, users will appreciate how Windows grants use of keyboard layouts native to their original language. Other uses will appreciate the different selection of cursors and the ability to add additional ones. Passwords. Since the computer in use may be shared with others, Passwords gives the almighty administrator the means to determine whether all users will share the same preferences and desktop settings or if users can customize preferences and desktop settings. That may be just fine for some, but most people require more than that especially in today's "connected" society. Today's users require full multimedia capabilities, a wide range of graphics tools, and accommodations for the various portables we now enjoy. These extras aren't included with "what comes out of the box," and the only way to get them is to accessorize.