Well there are several factors that should be taken into consideration when making your decision and my take on your best choice may surprise you. First thing you want to find out is pretty obvious. Do other people think it works well with your operating system type (XP, Vista 200 pro etc..). Some antiviruses work better with different operating systems. Now, you may ask... Well thats all well and good, but what do i want to know when doing these searches? Well some of those answers are obvious, and some not so much. Below is a break down f things to look for.
1.) Is it supported by your operating system version
2.) Is it very processor intensive? Do people say that they can do very little when the antivirus is on a live scan
3.) Are their Defenitions updated daily?
4.) Is the software a memory hog?
These are all things you can find on the web using google and typing something like "Is AVG a computer Hog?" You will be surprised how many people out there freely offer this information without any hassel just so others don't make the same mistake they did. So with that said, here are my picks for great Antivirus software and why I chose them.
1.) AVG Anti-Virus 9.0 !
2.) Trend Micro AntiVirus plus AntiSpyware 2010