Freeskills
http://tutorials.freeskills.com/v2l/firststeps/vid/relweb
A free online course which gives you access to a national recognised qualification. Takes you though finding your way around a computer, using software applications, sending and receiving email and using the Internet. You have to register to join the course but it is free.

How stuff works
http://www.howstuffworks.com/category.htm?cat=Comp
How stuff works is an excellent site. There is a computing category with very good explanations on how things like hard disks and networks work.