Setting spam assassin to capture viruses?

[Dragoncrest]

	Is there a way I can adjust by hand spam assassin's config file or one of 
the files it uses to detect spam so that it also will look for attachments 
and if it finds anything with the extension of pif, scr, exe, or com, it 
will automatically flag it as spam and toss it in my spam folder?  I want 
to set it to block certain types of attachments on email.  Or would that be 
better done with procmail?  Qpopper?  Just curious what's the best way to 
block these.  I figure if spam assassin will do it, I'll just adjust it so 
that it takes care of this for me.  Thanks.