I am not very computer minded, i have been given an old computer, it has no mouse, i bought a usb one and a ps/2 one and neither seem to fit, the is a hole very similar to the ps/2 connection but doesn't have a hole for the middle prong on the mouse? any help ???

any help ???

Sorry Rach, but we can't help if we don't know what we are dealing with. What is the make and model number of the computer?

It sounds like the plug you speak of might be a "s-video" connection, an old style method of getting the computer's video to a TV monitor. The mouse should connect to a connector next to (or right above or below) where the keyboard connects. PS/2 connections are often color coded as green for mouse and purple for the keyboard.