Microsoft has written Knowledge Base artice Q249249 on this subject:

"This article is an overview of how to migrate an Alpha-based primary domain controller (PDC) to an Intel-based PDC, including information on how to migrate the WINS and DHCP database like the existing shares and Access Control lists (ACLs). A prerequisite is the use of a backup domain controller (BDC).

This article contains no information on how to migrate programs. Programs use a different native code for Alpha processors than for Intel processors, and you must install new versions."