The proper way for me to create new network is to create a PDC useing 2008 r2 64bit and create a second backup DC then the 3rd server setup as a 2008 r2 64bit application server for exchange2008 std 64bit with this configuration will my 32bit pc's connect to the PDC knowing its setup as a 64 bit server or should I make the PDC a 32 bit server?

they will connect fine. 32 vs 64 bit only affects the server performance and applications that may be installed on it.Chris Morgan

Hello Joe, As you know, Windows Server 2008 R2 will be 64-bit only, but this refers to the supported processor architecture. Windows Server 2008 R2 will still enable 32-bit applications to be executed, Microsoft provides Windows 32-bit On Windows 64-bit (WOW64). So there is no need to worry about application compatibility. As promised, what is the WOW64 and what does it mean to managed apps that you run on 64bit machines? http://blogs.msdn.com/b/joshwil/archive/2004/03/11/88280.aspx Brent Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread. ”

Hello, there is no problem running a mix of 32bit and 64bit OS versions in a domain.Best regards Meinolf Weber Disclaimer: This posting is provided "AS IS" with no warranties or guarantees , and confers no rights.

thank you very much