I am going to be offering different platforms of hosting - ie Linux, Windows and ColdFusion - as well as with different panels - ie HELM. CPanel, and one more.

What do you think is the best way to display my hosting packages, by platform or by control panel?

I would probably go with displaying by control panel. That way, potential customers can specifically see the difference between the different packages. Novice customers most likely won't tell the exact differences between a Windows hosting platform and a Linux platform. By showing the control panels, you can at least show them what exactly is different.

Do a survey from your target market and ask them what they are looking for.

If they say "windows" hosting... then organize by os. If they say "cpanel" hosting, then organize by control panel.

Otherwise, organize by "value" or "service type".