I have been searching for a solution for a while now, and have not found the right one.
I was hoping you guys can help…
I have a simple landing page using flash on it, and I want to be able to detect if visitors to this LP have flash installed to view it with, and if not, I want them to be able for them to install Flash from this landing page with this pop-up below.

how can i do that for IE?
swfobject offers this capability
You can use hasPlayerVersion() to detect the version:
Checkout Step 3 on this page:
http://code.google.com/p/swfobject/wiki/documentation
to learn how to use swfobject to run your plugin installer