How do you detect if the iPrint client is installed with the Firefox browser?

When I use ...

function CheckForNetscapePlugin()
var i;
var numPlugins;

numPlugins = navigator.plugins.length;

for(i = 0; i < numPlugins; i++)
if(navigator.plugins[i].name == "npnipp Dynamic Link Library")
return true;
return false;

After the iPrint client is installed it still prompts me to install it.

Any ideas?

Dan :-)