Right now, h.264 is going to be your best option for codecs. I don't recommend having HD resolution on the web as the cost/performance ratio is not good. The other advantage of h.264 is that it can be played through the new Flash player as well as QT. This is really important for compatibility.
One option is to use a service like Vimeo or *gasp* youtube. They now offer "high-quality" versions of your presentation and they will get the data transfer hit instead your host. Then you could use something like blogspot to create your website and embed the video from Vimeo on the blog.
-gl
Freelance Designer
http://www.georgeloch.com