Hi
Just spotted that your mail has not been answered!
First for a site of 6 pages I would consider building it in plain HTML but this might not be possible depending on what functionality is required.
Screens can be very large these days and you would have large file sizes for the images unless you compromise with software that can boost the image size. You might be able to adapt this
www.buildinternet.com/project/supersized/ (I do not know if a drupal version is available).
There certainly are Joomla templates available for this kind of site.
www.joomspirit.com/template-joomla/template-full-screen-4/ www.joomspirit.com/template-joomla/template-full-screen/ (joomspirit have 2 more full size background templates; the transparency of the foreground can be altered)
demo.pure-joomla.com/ (PJ Epoch)
Your client would need to be able to resize an image upload it to the media manager and enter the path of the image into the module. This does a good job of preparing the images
www.webresizer.com/resizer/ Sorry but I do not have a drupal solution but that does not mean there is not one!
If a Joomla solution would suite your needs I would be happy to build the six page site for you if you need it quickly.
Regards