That same virus also doesn't affect programs or files belonging to other users on the box, so it is naturally better retained. Additionally, in order to attack Linux, the writer must be able to attach itself to executables, which run with system privileges. Only a token amount of Linux executables have root type privileges.
I would agree that if Linux did run the world, there certainly would be many more attacks on that operating system than there are today. There might even be a new breed of hackers and virus folk in place, much more intelligent and sophisticated than the current breed. Those who write viruses and worms want to impact as many people as possible, and certainly one of the main reasons there are more viruses on Windows than any other platform is because there are more people using PCs running Windows than any other platform. The bottom line is that these idiots want to hurt as many folks as possible, so they focus on Microsoft.
Though Linux is a better OS than Windows will ever be, as its popularity increases, I don't think anyone would disagree, so will its susceptibility to virus attacks. On the other hand, the Linux/open source community will probably do a better job in proactively fighting the virus fires than Microsoft can ever do.
This was first published in March 2004