Cannot remove it in Add and remove programs, any advice would be greatly appreciated
Does not show with CCleaner,
I think Slick Rick has answered my problem, many thanks for everybody's help

Open Windows Defender, go to Tools>Options and scroll down to Administrator Options - remove tick from "Use Windows Defender"
and click Save.

You may get an alert from Windows Security; you can click on "change the way security center alerts me" and disable these notifications if you so wish.

In the start menu search bar type

services

and click on the result

scroll down to "Windows Defender" and double click the entry; set the start up type to "disabled" and click apply, then ok. Exit Services.

in the start menu search bar, type

msconfig

and click on misconfig.exe; select the startup tab and remove the tick next to Windows Defender; click apply, ok.

You can't it is built into vista. If you do not want to use it you go into services and shut it down. By the way i have heard of people that meesed up their computers by trying to remove it. It would be nice if microsoft would tell people about this ahead of time it would save a lot of headaches.

Uninstall it, using an Uninstaller program. There is a free one in tools in CCleaner. The second one is not free, but very good (Tip-when it says re-start computer, say no).