SharePoint Migration from 2003 to 2007: Leave the clutter behind.

This has come up several times recently, and I think it's another case of the "Microsoft offers it so we should use it" mentality.  There are indeed tools and utilities for migrating your existing farm -- or content database(s), or site collection(s) from 2003 to 2007; there are even procedures for upgrading your SharePoint farm to the new version.

Having been all over that mess, I can't recommend it.

In fact, we almost always advise not migrating everything in bulk, in favor of having the users themselves bring over their relevant content.

Here's an analogy:  when you build a new house, you don't build it around the old one and hope everything fits.  You build in a new location (or perhaps the old if you're demolishing first), and then take what you want and place it where it should go in the new house.  Along the way, you discover a lot of things that you don't need; as a result, they get thrown away or given to someone else, and you have less clutter.

Of course there are exceptions, but -- generally speaking -- this approach (a) puts responsibility in the hands of the business users who actually *care* about their content, and (b) doesn't bind you to the old way of doing things.  It's a chance to go forward without the baggage of the past, to cash in on hindsight, to invent new cliches... and it shows you what content people are actually using.