WinXP superfluous virus protectors

HELP needed to remove "antivirus" programs:
1/ AVAST. Operates annoyingly. No removal tools.
2/ Microsoft Security Essentials. Keeps inactive red logo even when alternate antivirus active.
This makes them viruses!
Not in "Add or Remove Programs"... The "Avast" directory contents are not removable in TCC. REGEDIT cannot remove parts of Avast, either. I presume what's left of the Avast virus is loaded on log-in to prevent brute force .

BRW, I succeeded in removing the Microsoft Security Essentials.