I wanted to add, I have used both Norton (just the AV program, not the FULL
installation) and also McAffee. I also had System Mechanic. All of them
permitted Windows defender to be installed and to run. However I found that I
do not like Nortons, as viruses slipped by it more than once. I do not like
McAffee because it has so many sub programs running (check it in task
manager) and it slowed my computer down alot.
I have other software to protect my computer from spyware and other tools to
clean up things like cookies and internet browsing cache and such. But I did
want something small to trust, and I use Windows Defender - trustworthy
program offered by Micorosoft. And I am also using AVG free version as my AV
software - it is small and also reliable and doesnt slow me down at all.
There are so many available products, it can be confusing. Alot of these
programs tho, come with so much other stuff bundled into it - it can really
make the computer slow and so then everything I try to do is frustrating with
hangs and slow opening or saving.
I am happy with what I have. Spybot Search and Destroy, Tune up Utilities
2007, Windows Defender and Windows firewall still active - and also AVG free
antivirus program.
Hope this helps!