HDMI is a digital interface which can carry encrypted audio and video. VGA is an Analog connection which can carry RGB channels, vertical an horizontal sync, and some other things.
So you are speaking about different languages. And this means you will not just need an "adapter", you need a converter.
This also means that the resulting image quality will be influenced by the converter's quality.
Doing some research, I found a converter sold by Startech, called VGAHD2HDMI. It was mentioned in another forum as a cheap option (US$192). There are also USB to HDMI adapters.
I don't know if any of them support full HD input.
I am not an expert on HDTVs, but I haven't seen any without VGA input.
Luck,
Rodrigo