1. The simplest, most effective and reliable method is use anti-virus software.


2. Netstat -an checks if there are external connections. Here we should note that before we check all connections, we should turnn off all internet applications such as web browser, MSN. If external connection exists, it may not necessarily be infected with virus. We can track the IP source online and make simple judgment. But this is not necessarily accurate.



3. Use network data capturing tools to see whether exists suspicious outside data transmission.


4. Check startup items. Run ‘msconfig’ and check if any suspicious startup programs exist. If there is any, check the program file.


5. Right click on 'My Computer' and select 'Administraters' -> 'Services' to check if any suspicious services exist. We can search most of the services through internet and find out their functions. If we can confirm a service is virus, we can right click on the service and select 'Property' to check if any executable file exists. If yes, then delete the files and corresponding services from the registry.