Linux is not new, its roots can be traced back to 1991 and the originator Linus Torvalds. It is in fact derived from Unix which goes even further back. SUSE Linux, or Open SUSE as its now known can be traced back to 1994. (SUSE incidently is a German acronym for Software und System Entwicklung). All flavours of Linux can be divided into two main groups. Open SUSE is in the group based on the RPM package manager. The other group which has Debian at its heart, are based on the APT package manager. the most popular package in this group today is Ubuntu. The diagram shows the ancestry of the most common Linux Distros in use today.
As a novice should I worry about which package manager, and hence flavour, of Linux to use? The answer is no. Then does the choice influence the software applications that are available? Again the answer is no. Popular applications are packaged for both APT (.deb) and RPM (.rpm) based systems, and failing that, if you have managed to find a particularly obscure piece of software, you can download the source and compile it yourself. In fact, while I'm trying to dispel some of the myths surrounding Linux, since you are not tied to a particular commercial brand, the choice of applications is probably much wider than you may be used to.
Will my machine run Linux? If it is currently running windows, then yes. Even if you have an old machine, that can no longer cope with the latest Operating Systems, because of memory limits etc. Its still likely you can breath new life into the machine by using one of the smaller Linux offerings.
What about viruses? I won't say it isn't a problem, that would be to invite trouble, but it is almost a non problem provided you are careful. As Linux is based in Unix based, its biggest selling point is security.