upgrade my primary domain controller 2003 std edition to 2008 std edition

i have primary domain controller 2003 5 rolles installed  additional dns domain global catlog 2008 std

also have member  mail exchange 2007 os server 2003& ocs 2007 os 2003

i plan upgarde primary domain controller 2003 to  2008 out losing data or roles how can "detailed steps pls" 

your upgrade path depend on whether doing in-place upgrade or standing parallel domain controller. want make sure meet system requirements, , perform backup of boot , system partitions , system state. in order prepare domain 2008 log on schema master , run adprep on forest , if intent use read domain controller run adprep /rodcprep command. log on infrastructure master , run adprep on domain , group policy prep. can upgrade primary domain controller 2008 or promote 2008 member server new dc. there supported upgrade paths, , should able go 2003 2008 without losing data it's idea take , test before performing upgrade. upgrade should transparent exchange , ocs users if have addition dc available serve request during upgrade.

i've included links think should read. contain step step instructions need , other information consider before carrying out upgrade.

http://technet.microsoft.com/en-us/library/upgrade-domain-controllers-to-windows-server-2008-r2%28v=ws.10%29.aspx#bkmk_upgrade

http://technet.microsoft.com/en-us/library/dd379511%28ws.10%29.aspx

Windows Server  >  Migration