The E8400 is a better choice then current quad cores. It has SSE4 which greatly improves graphics work (more then doubles the performance in some encoding tests) and is being patched into CS3 as we speak... It is also natively faster.
You could wait a month for the SSE4 quad cores to arrive. when the architecture is identical, quad core is better for graphics. its just that the q6600 is over a year old and the E8400 is a month old... The Q9### CPUs are gonna be your best choice... its just not out yet.
EDIT: from wikipedia "Yorkfield CPUs were expected to be released in January 2008. However, the release of Yorkfield was delayed to March 15th 2008"
So if you can wait until march 15th you can get a new architecture quad core... and intel says they will cost the SAME as existing quad cores of the same speed. (which they have already done with the E8400 and its wolfdale family) They are meant to be quick replacements.
So wait until middle of march for a quad core and you should get a much much faster CPU for your type of work.
I would say that if you get one today:
CPU: E8400
Motherboard: Asus P35 based motherboard of your choice
http://www.newegg.com/Product/...ption=asus+p35&x=0&y=0
Asus has unmatched quality. And you probably don't want to spend hours troubleshooting why your system doesn't work... They are also engrish free...
45 megapixel camera? damn... 8GB (or more!) might be in order for pictures THAT big. I am not 100% sure but there is a good chance of it. You should look online.
Seasonic PSU or an Antec earthwatts (which is a rebranded seasonic)... at least 400 watts... don't bother going over 500watts as it is not gonna be needed.
video card:
Do you game AT ALL? Video card has ABSOLUTELY NOTHING TO DO WITH VIDEO EDITING.
Photoshop and encoding does NOT use video card for ANYTHING!
The ONLY reason to buy an expensive video card is for gaming!
I would NOT use a built in one on the mobo since they are crap... but a 50$ video card is good enough. like a geforce 6 or 7. Any non game I build a PC for gets a 50$ GF6 or 7 video card. It gives them quality drivers and image quality (compared to built in one)... but it wouldn't play newer games (which they don't need)...
There is also the issue of being easily replaceable if needed.