AD migration to AD Server 2003

Your organization (Company A) has just acquired another organization (Company B). You have been asked to come up with a plan to join the new organizations network to your organization?s HQ office.

Describe/Diagram in detail on how you would integrate company B with Company A?
Company A is a Windows 2003 Server Environment
Company has the following services - Active Directory, DNS, DHCP, FTP, HTTP, and SMTP
Company B is a Windows 2003 Server Environment.
Company B has 500 employees
Company B must connect to all of Company A?s Resources.

Include Subnets and any applicable networking equipment
Budget is no objective.