The rule of thumb is one anti virus and one firewall.If more then one AV is installed make sure only one is active,same goes for a firewall.
You can have more then one anti spyware,in fact it is a good idea to do so since one may catch that another misses.I use
AVG ANTI SPYWARE
I do not have Windows Defender cause I don't like MS products.
I've been told to avoid conflict that you should have only 1 anti-virus program on your computer. When it comes to spyware can you have more than one spyware program installed on your computer?
Does anyone with a Windows PC have Windows Defender installed on their computer and if so is it any good? A syndicated article in my local paper today written by a techno geek recommended owners of computers having Windows XP to install Windows Defender.