I disagree strongly, the Viruses that sado's sit and make in their mums basements do not do any damage to *nix machines, Windows is heavily targeted.
Linux is a stable strong and robust environment, having the ability to run windows apps with emulators and still carry the linux kernel to do nearly anything else, when you install a VM on a windows box the performance of the host machine is degraded considerably.
The main difference for most users is the sheer amount of softwares available for Windows makes it an easy option, however, as mentioned, anything windows can do *nix can do 5x faster, and still be open source, free to get and update ( most distros ).
Some linux distros however, are not what I would call user friendly, it takes some time to get used to the way things work, sometimes new hardware can be a headache, more and more equipment is supported natively by the *nix kernel as standard, but if it's not, chances are the company who made it don't have a budget for *nix environments, and so you'l be pretty stuck.
I use windows most of the time, however, I use Linux aswell, and enjoy doing so.
If Linux was insecure then 60% of the internet wouldn't rely on it would they....
As for "Longhorn/Vista" or whatever they eventually call it, at this moment in time, it's total and utter crap, not to mention the fact, its been on it's way for nearly 4 years now. It'll be mostly eye candy when it does come out, and still smacking of XP SP6, if the misses was a little more competent on the pc I swear I'd throw windows straight in the bin, and never look back.