What is the best user-friendly Linux operating system?

I've been using Windows 98 SE for almost eight years now, and I'm upgrading my old computer, which is a Pentium II, to a used Pentium III, I don't have that much money to buy a new Pentium IV PC, so I'm thinking of using a Linux operating system, since one of my friends says that Linux is less susceptible to viruses than Windows, and I don't wanna pay Bill Gates anymore, but being not that knowledgeable with computers, I need an Linux operating system that's user-friendly...