I use Avira Free combined with Syagte Personal Firewall in xp and Comodo in win7 on my wife's laptop.
As for me i mostly never use windows. i use only Linux whenever i can. (the only drawback is games. you need windows for games such as NFS etc, others like quake etc runs on linux).
My personal Linux is Mandriva, started off with RedHat in ~2000, but later on switched to Mandrake (old name of mandriva)
avast internet security with license ;) After testing over 13 av's with my PC this one seemed balanced overall. Altho I believe our own quickheal is the best av out there followed by kaspersky and symantec.
Quick Heal is an Indian company founded ~1993. So if you are purchasing an AV quickheal is a good choice, it is a good AV + we will be supporting Made in India products also.
Many of my friends are using Licensed QuickHeal after i introduced it to them on 2005, and they are happy.
I'm using this on my older Dell Laptop. Actually my company uses this in the office and on the ships so I got hold of the licence key. However it expires in December. This is a very good option in paid. Quite VFM and good performance.