[CentOS] Internet threat management package

... Looking for a recommendation for a commercial threat management 
package.  ( Think antivirus / antispy / anti-rootkit -- all rolled into 
one engine ), similar to this product: 
http://usa.kaspersky.com/products_services/work-space-security.php, 
which currently only supports one kernel for FC6, and RHEL4, officially.

Here's the background.  Need to make a decision and investment for a 
hybrid linux/windows network, with a Samba file server running Centos5.  
Would like to invest a single product, rather than multiple products, 
especially since that implies that I'm not giving money to companies 
that only provide software for Windows.  (or, supporting companies that 
provide software solutions for Linux, depending on how you look at it.)

Not even sure if I have the right idea.  I would assume that Linux 
clients are not completely invulnerable to virii, spyware, and rootkits, 
and that it would make sense, in a small corporate environment to guard 
against them, the same as Windows machines... but the lack of options 
seems to suggest otherwise?


Anyone have any tips, advice, or recommendations?

Thanks!!

-- J.