As Alastair has pounted out, Sketchup is a very useful program, free, and simple to use. I'm a professional draughtsman and wish some of the programs I use (some costing in the 5 figure range and up) where as simple to use. It has some shortcomings but for the average user, would be the program of choice of the cheepies available, and its free. I use it a home in preference to others I have for selected drawing.
If you want simple linework for producing charts, electrical diagrams and schematics and the such-like then try the drawing utility within Microsoft Word. Simple to use, text no problem with a huge choice of fonts, and a library of basic symbols, arrows etc. Output in Word format, pdf, to printer, most of whatever you may want. Already there in a program which probable came with your computer and no body told you it was there.
Hope this helps some
Kiwi