Question : Windows 2000, 2008 and Exchange 2010

my DC is running under 2000, can I still have windows 2008 and exchange 2010 running without having issue with my Active directory ?

Also, is there any tools to transfer Exchange 2000 to 2010 ?

Answer : Windows 2000, 2008 and Exchange 2010

You need to upgrade your 2000DC to 2003.     Active Directory must be at Windows Server 2003 forest functionality mode or higher.

http://technet.microsoft.com/en-us/library/aa996719.aspx

Migrate Exchange 2000 to 2003 or 2007 then to 2010.