Seb7 - 4:25 am on Feb 23, 2012 (gmt 0)

You can send a message to all the users of these bot machines just by using a javascript alert box.

I suggest adding a honey pot for the bot to navigate to (a hidden link to another page), where the hidden page simply displays a javascript alert saying 'hey, your machine seems to be infected with a virus'.

Though IE can be controlled in a hidden window, any alert boxes still get shown on the desktop.