Site Design Question (2 installs or 1)

I am rebuilding a family site on WordPress. I’ve only just begun so I still have time to scrap and redesign. I want two main aspects of the site, pictures (nextgen plugin) and family tree data (rootspersona plugin). The index page of my domain is not wordpress, but everything else will be.

Right now I have two wordpress installations, mydomain.com/photos and mydomain.com/tree. I would really like it this way…to have all my albums and galleries under “photos” and have all family tree stuff under the “tree” folder.

Is there a way to make this work under one installation while still keeping with what I want and keeping each area under its own specific folder? I thought that perhaps installing in mydomain.com/site and then seeing if I could separate beneath this directory, but I’m not sure how that would work.

Any thoughts would be appreciated.

Sel