Hello Vicky,
I will explain to you my own experience on this subject, and you will be able to take your own decision, also taking in consideration the next responses to this thread. 
I had used many anti-virus in the past, some of them paid, and some of them free. The last one was Panda Internet Security 2007 Platinum, which was unninstalled from my machines just about 3 or 4 days ago, because it begins to “find” viruses on files that I have total certainty that was not infected (comproved through analysis on virustotal.com, through inumerous engines).
This caused inumerous problems to me, because Panda is not interactive at the momment of detection, and it simply try to clear and/or sends the file to quarantine. The result: I had many files corrupted and almost had to format some of my machines. As I have paid for the solution, and the licence will expire only on January/2008, I tried to contact Panda Technical Support in Brazil, that is totally inefficient. And if you try to ask Panda Technical Support from Europe or USA, for example, they simply delivered back your problem to local representative, i.e., nothing was done to solve my issues. It seems that a Panda customer is obligated to obtain technical support only in your country, even if they are totally inefficient.
Panda Solution also blocked all my internet and LAN access, and there was not any rule that solve it problem, nor the Firewall deactivation. Only the total deactivation of Panda was solving the problem. And, again, Panda Technical Support was not able to solve the problem.
So, I have decided to unninstall Panda of all of my machines, and have choosed two applications:
- Comodo Firewall Pro V3
A really great firewall, easy to install and manage, with a beautiful interface and a HIPS integrated system. It has passed on all tests I have made at PcFlank and ShieldsUp, with all my ports being showed as “stealth”. It has also passed on the trojan test and on the leak test. The list of features are very cool, and you can take a look at that to see with your own eyes.
- Avira AntiVir PersonalEdition Classic (freeware
A great anti-virus, with a good detection rate, easy to install and manage, daily updates, rootkit detection and a good technical support, even being a free product, through a support forum both in deutsch and english. It consumes very lower resources of the system, too.
For me, the above mentioned combination is being very useful and powerful, until CAVS V3 be released, of course. (CLY)
Complement the above combination with Comodo BOClean, and I think that you will be extremely protected, combining, of course, with good practices while navigation, etc.
Regards.