size and pixel aspect ratio of Encore background
 

I'm hiring a graphics artist to design menu pages and want to be sure of the correct size. Project was shot Hi Def at 1920 X 1080 and DVD will be released in both Standard widescreen DVD, and Blu Ray. I'm not sure of the size and pixel aspect ratio for the Standard Widescreen version.

Go to Photoshop, and click File>New>scroll down to the video presets. This is a good starting point..

Just let him build a menu for the BluRay disk. In Encore you can output with the same menu to DVD.

The above advice is good, but here are the figures, just in case your workflow needs it:

PAL is 720 x 576, both 4:3 and widescreen
D1/DV PAL PAR 1.09
D1/DV PAL Widescreen PAR 1.46

Adobe has a good paper on this, at:

Adobe After Effects CS4 * Pixel aspect ratio and frame aspect ratio

They go into great detail about it, as well as giving image sizes when working with square pixels. It can be a confusing subject, especially so when Adobe themselves (as well as others) were using not-quite-precise PARs before CS4. Give it a look.