I am getting ready for my next MCP 70-284 Exchange, so I have studied ADMT v1 and v2 carefully.
Yes, ADMT v2 supports W2003 and W2000 interforest and intraforest migration, both ways W2000 to W2003 and vice versa.
It will migrate the User Password and SID (e.g. permissions, Group memberships, etc).
SID is short for Security Identifier. A SID is a unique ID string (e.g., S-1-5-21-1454471165-1004336348-1606980848-5555) that is assigned to each account created in a domain or on a local computer.
SID is how the operating system keeps track of accounts. For example, you can rename the Administrator account on a computer and still use that account to function as an administrator because Windows knows this account is the Administrator account because the SID remains the same regardless of the account name.