Well, i think to have a fair comment, there isn't such a thing called safe.
I serious doubt Linux is safe. Its probably not getting much attention yet. There was an NSA report listing which OS has the least vulnerability.
But i think a more serious look at it would be the company behind the OS. I'm saying this not because i work for Microsoft.
Think about this. How many of us out there, has the ability to patch your own codes. As in, if you discover a vulnerability, do you have the ability to correct and bits and prepare an attack? I can easily say more than 99% don't know how to. Microsoft has a security response unit running round the clock to work on such security issues.
They are currently working round the clock for an IE7 vulnerability. And they have a mechanism to distribute this to all machines.
I have not seen another operating system with a comprehensive update mechanism like Microsoft Update.
There are times where things *** up, but let give them the dued credit.
Linux is safe?? Think again. I highly doubt Linux is bullet proof, but once hit, can i respond as fast? And if there is a response unit to patch codes, which distribution, which version, do you get notified?
I ever heard from a security guru, an operating system is as secure as how often you update it, and keep it updated. No one in this world dare claims their software is safe. :-)