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. This article will describe this recent phenomenon and describe some of its benefits for the software using community. In a nutshell, open source software is software made by everyone - for everyone. The hopes behind its development is that through its open access, it will evolve into something that represents the true desires of computer users. In programming, it's sometimes required to work with unknown pieces of data. That's when conditions come in handy. 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. Identifying Compressed Files Most files are compressed in .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. If you're familiar with MS-DOS at all, you'll recall that it's a command-driven operating system that performs functions issued at the C:> prompt. The only way to get an MS-DOS computer to do something was to type a command at this prompt and if you can imagine, it was a rather cumbersome way to use a computer. When you think about upgrading your computer to a new operating system, be careful to make sure that you have the necessary hardware components. 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.