HuskyPup - 1:06 am on Mar 16, 2011 (gmt 0)
or taking the opportunity to alter the structure - ie group pages in folders by topic?
If I am understanding you correctly do not do this until after the Search Engines have absorbed the new domain running under the old URL structure.
If you move all the pertinent information and change the URL structure you will blow the thing apart and lose a lot of G'love.
Quite simply, move exactly all the applicable stuff sideways under the same URL structure, let the SEs absorb it and then wait 2-3 months before changing stuff and then do it gently, not a massive overnight change.