Migration of mailboxes in MSExchange

Hi,
Please, advice me on the following.

I have Windows 2000 as a domain controller. MSExchnage5.5 runs in a NT server in this domain. ADC is installed in Win2k already.

I created MS exchange 2000 server on a windows 2000 member server on thesame windows domain. But, the organization and site names of Exchnage server are different from the Exchange5.5
Can anyone explain the procedure how should I proceed to migrate the mailboxes from 5.5 to Exchange 2000?

I tried Sp2 migration wizard. But, the migration process is failure.

Can you help me on this?

Thanks.
Magesh