dll - This extension indicates a Dynamic Link Library which may contain additional programming code for software. Many different programs often share Dynamic Link Libraries and you'll find a bunch of them in the Windows/System directory (but don't ever delete them)! .exe - This extension indicates a program or an application like Microsoft Word, Internet Explorer, or Outlook Express. Anti-virus/anti-spyware software will stop malicious code from downloading and installing onto your computer while you peruse the Internet. Known as viruses, worms, or spyware, this malicious code can destroy important files and render your computer good for only one thing: sending sensitive data back to the server of an identity thief. A virus originating from the boot sector of a computer is a boot-sector virus and this nasty devil does its dirty work the moment a computer is turned on. A virus that attaches itself to (infects) other programs is a file virus and activates the moment that an infected program starts. File viruses may also be referred to as parasitic viruses, however should a virus work from both the boot-sector and from an infected program, the virus is then known as a multipartite virus. The above illustrations were just a couple of examples of how far computer technology has grown, and how far we've pushed "user-friendliness" to its limit. Eventually, the keyboard and mouse will have to play a role when computer newbies have to work with one as a cash register, as a hotel booking program, or as a library's catalog system. We tried to upgrade one of our Windows 98 machines to Windows XP, but we were cautioned that the former may not be hardware compatible with XP technology. Apparently, the Windows XP operating system requires components that weren't developed at the time Windows 98 was distributed and if we were to install Windows XP on this machine anyway, the new operating system would look for hardware that the computer didn't have. And this is what puts open source projects far ahead of its monetized competition. As a software user, this means you can contribute to an open source project as well, and help to develop it into a product that reflects your direct preferences. You aren't "stuck" using open source software the way you would be stuck using an expensive word processor or database.