Disconnect the infected machine from any and all computer networks (the Internet and/or Local Area Network). If possible use a PS/2 based mouse and keyboard rather than USB (if you have to boot to DOS or Linux there may not be USB drivers). Have these programs ready to run off removable media (floppy, CD, USB flash drive): a disk imaging program, a program to control auto-started programs, a process monitor, a utility to disable Browser Helper Objects (BHOs) and a firewall. (more on this below) It is best to run this software from removable media both to insure it is not compromised and because some malware may prevent the use of equivalent Windows based software on the infected machine. Also, there are a number of steps that should be taken before connecting the infected machine to the Internet to download any other software
Credit : Michael Horowitz : http://www.michaelhorowitz.com/removespyware.html
