The first line of defense is not the security programs but the users computer habits and actions.
All in all the only differences between payed versions and free versions is the add-ons but to most this is not needed or truly wanted for the program to perform as promised, or it (the add-on) can also be free from somewhere as well. AVG Free - Download AVG Anti-Virus Free Edition for Windows XP and Vista
In the above link if one was to take the time to read it there is a comparison chart showing the differences between the freebie and the paid for versions.
AVG is the anti/virus program this is what you get for free and it is exactly the same for the paid for versions. The different things is that you get a firewall and anti spam program and a root kit detector in the paid for versions...all of which can be gotten for free as well . So all in all you are paying for them to put all the needed programs together for you in a single package.... and running updates for you! That is all you are paying for....not a better version just more add-ons in a single package. and when the comparisons are done they are done as whole programs and not seperated to the actual program against program but by program package against program package. So in reality if I was to compare the free package against the paid for package there would be difference. but soely upon the differences between the packages.
The subjected theory of buying something makes it better is just not true when it comes to anti virus/malware/spyware programs. I have been using the free versions for almost a decade now and have never been attacked by a virus or any super malware/spyware varmints. I am on 24/7 and surf constantly, plus use torrents and Peer2peer programs and also instant messaging and on line gaming with all kinds of scripting involved....
Now if you wish to be lazy and overconfident then by all means, spend your money on something to take up for your short comings. It is after all your money. But if you wish to be prudent and savy..well learn the differences between what is offered and what the comparisons are....
Avira... for anti-virus....top 5 for antivirus program......beat AVG
comodo firewall...top of the line firewall
Sophos anti-root kit program
Spybot S&D anti malware/spyware program
Spywareblaster....anti spam and spyware program
Ccleaner...file cleaner and top line reg cleaner as well
ATF cleaner or Clean up....the best temp files cleaners around
WinPatrol...registry and program protection plus more
add to this a regular scan from PCpitstop or trendmicro and you have one heck of a package.
Now these have all been out for years and all are free. I will put them up against any of the paid for versions.
On top of this...they do not take over your computer like Symantic/Norton or Computer Associates or even McAfee programs do. Norton has caused all most as much problems as any virus or spyware/malware program out there with its conflicts and over riding controls...McAfee ...the same! and Computer Associates with their programs is right there along side of the other two!