I went through the process of migrating from PS2002 to P2003 recently.
The PS2003 Installation Guide provides fairly good guidance about the
process. Assuming a SQL Server implementation, I would strongly urge
you to make certain that you backup all of your data files, including
your SQL databases prior to initiating any migration activity. Although
the PSmigrate process is non-destructive, this is a protracted process
and there is ample room for mistakes along the way. One word of
caution. I found that after having migrated my Project Server data, as
well as Sharepoint Team Services sites(non-project related), the
document libraries that were not Project related contain a "Comments"
field in the document properties. This causes a fault to be thrown when
someone attempts to view or edit a document's properties. That is
really the only gotcha that I have run into since the migration in the
latter part of December. One final thought, review the Disaster and
Recovery guide for PS2003, as there are some differences in the way in
which ProjectServer data is managed/stored, and you will want to ensure
that you have a backup and recovery plan for your data. Good luck.
