Configuration file

A text file which some applications use to store settings

DLL

Dynamic Link Libraries.  These are 'support' files used by some applications.  Like configuration files, you never use these directly yourself, but they are essential to the functioning of the software application.  If you delete them, the application won't run.

Executables

Also known as 'programs' or 'applications'. 

Explorer

The Windows 9x utility which allows you to examine and manipulate files on your computer.  Also sometimes called File Manager.

File

These are usually specific documents created by applications.

Folder

Container objects, as the name suggests.  They can contain files, or other folders.

Help File

Documents (usually hypertext in nature) which act as on-line manuals for applications.  They act as executable files (ie you can 'run' them).

Icon

Graphic images 32x32 pixels in size, usually used to represent applications

String

In computer terms, this is any collection of letters or numbers.

Wildcard

Symbols used to represent variable data - especially in searches

VGA, pixel, resolution

A single 'dot' on the computer screen.  'Normal' screen resulutions range from VGA (Video Graphics Array) - 600X480 and SVGA (Super VGA) - 800 X 640.  SVGA resolution means that the screen is displaying 800 pixels per inch horisontally, and 640 pixels vertically.