Upgrade of Domain from 2003 32bit to 2008 R2 64 bit - Urgent

Here is the Information about our Company's Current Domain:

PDC - Based on Windows Server 2003 32 bit, with FSMO rules, AD, DHCP & DNS

ADC- Based on Windows Server 2003 32 bit, with AD, DHCP & DNS

I make ready Two Servers with Windows Server 2008 R2 64 bit, Please Give me step by Step information to Configure/Migrate Domain on these new Machines.