How to Develop a Anti Virus Using c# or vb .net

Sorry, but the fact that you're even asking this question tells me you're not qualified to write an antivirus and I have very high doubts in your ability to analyze viruses and update your signature library regularly.

Free? You get what you pay for.

HI I am Taha;
an antivirus application devides into 2 general parts:
1-services;
2-applications;
Services:
some task that must be run continously in background of the OS tasks are developed in this way;
for example firewall - file change checking and ....
Apllications:
a panel to control - monitor - and the user tasks in this sectin;
these 2 sides talk with each other;
they connect to each other adn the services' activity are shown in the application;
you need a database to store the viruses information to compare the app. to them to find the viruses;
other tricks can be add to find the virses but basicly is comparing between;
some other ways to find viruses :
1- finding a cyclic activity inside an app; (e.g. an unlimited cycle)
2- finding a command in an app. that is not common (e.g. accessing to some part os memory)
3- inspecting the actvity of an app(e.g. app is doing strange task like deleting files in general )
4- controling the task manager to have it monitored by antivirus to prevent/let an app to be run (e.g. antivirus blocks a autorun app but contorling the system task manager)
and other ways also that they are too much to expalne;
I am agree with you ; this project you said is good and I support ya ;)
have a good time ;
ENG.Mohammd > inventor of SIIS Systems;
yahoo ID: *REMOVED*
yahoo mail : *REMOVED*