Can I have a Windows Vista/7 gadget where the app is loaded from a PHP made website on my own host?
Also, can I have one advertisement in the gadget, to make money, like using Google AdSense?
this should be possible, i just had a quick look at the gadget api and it seems that the a gadget requires a manifest for meta info and an html page, which i would bet that it's perfectly possible to load external content aswell as javascript and ajax.
I would in turn read the ALL the Terms and conditions as there will be restrictions on monetizing your gadget such as: http://msdn.microsoft.com/en-us/library/aa974179.aspx