How to choose a good antivirus?

There are many antivirus program in the world. Example: AVG from Grisoft, Norton from Symantec etc. The good antivirus must be got by user. Technology of virus go forward so far away leave the technology of antivirus. So, everyday virus maker make a new virus with a new varian.

As we know the system operation(Microsoft, Linux, Unix etc) is more difficult to organize and we need to security update so often. Choosing antivirus isnot simple, there are some method.

1. Update frequency.
2. Necessity of system operation which are had by PC.
3. Equipment of defense which are ordered
4. Update cost
5. Effective to detect virus, worm or trojan horse
6. Efective to cure file which have been infected
7. Activity report
8. Technical support
9. Consider about research, costumer support and service.
By use this program, user will get the best antivirus program. Although there is no perfect antivirus.