Hybrid Homes

Wondered if any other people here have attempted a similar setup. We have a large AD Network running 2008 with Unix DNS and an OD network running leopard. At present the two directories are separate but we are hoping to change so that all users authenticate to AD rather than OD eliminating the need for separate accounts for the two systems. I have looked at the magic triangle cylinder of destiny etc and they dont seem to fit what we want which is when users login to the macs they authenticate via AD but their mac mobile account resides on the OS X server and when they login to a PC's their PC account is located on the AD server. The other issue which Im not sure if this has been resolved yet is that our AD network uses .local, is this still an issue?