What is the best antivirus for Windows XP Professional?

i need to be able to fight all threats , viruses and spyware programms ...

What is the best antivirus for Windows XP Professional?symatec

Any one of those while working online...

1.Mcafee internet security suite 2007(30days trial)

2.Norton internet security suite 2007

3.AVG Internet security suite2007(30 days trial)

4.trend micro antivirus ,anti-spywares(trial)

6.CA(computer associates ) anti-virus (trial)

7.AVS(Active Virus Schield) antivirus (trial)

all of those have some advantages and disadvantages, one cann't gurrantee that it is the best, some make systems slow some are slow in scan ,some can consume alot of application memory, some can give unnecessary warning from time to time, some can slow down system start-up and web surfing ..you can download and try one by one and gather your own experience and select which is best for your work and protection.

What is the best antivirus for Windows XP Professional?vista

At the university where I work, our Senior LAN installs Symantec Antivirus on all the computers for faculty, staff and student computer classrooms.
i like AVG

its free easy to deal with and latest updates easily available...
AVG free edition. its's free, regularly updated and does not freeze the pc like Norton. in other words, free and yet rivals all commercial anti virus software
Zone Alarm Security Suite (firewall + antivirus + anti spyware + ad remover + cache cleaner + privacy and identity protector, all in one suite).