Make regular backup copies of all your work and system configurations. Install and use anti-virus software regularly. Update your anti-virus software regularly so it can detect new viruses. Information on Viruses Dr. Solomon's War on Viruses Computer Viruses and Security Computer Trojans Computer Trojans are simply malicious computer programs disguised as something useful. The major difference between viruses and Trojans is that viruses reproduce, while a Trojan is just a one time program which executes its payload as soon as the Trojan is executed.
Trojans are the most common way of bringing a virus into a system.
A current example of a Trojan is a program called pkz300b.exe which disguises itself as an archiving utility, but when run it will delete your entire hard drive. Computer Worms Computer Worms are reproducing programs that run independantly and travel across network connections. The main difference between viruses and worms is the method in which they reproduce and spread. A virus is dependant upon a host file or boot sector, and the transfer of files between machines to spread, while a worm can run completely independently and spread of its own will through network connections. Overnight the worm copied itself across the internet, infecting every Sun-3 and VAX system with so many copies of itself that the systems were unusable.