I have two books:

Sams Microsoft SharePoint 2003 and
Microsoft SharePoint Products and Tecnologies Resource Kit

The resource kit (written by non other than our own Bill English) is by far the superior book. I mean anything else is really a waste of time.

Start with the "SharePoint Products and Technologies Resource Kit' by Bill English

Just so everyone knows, there were 11 co-authors on this book, so 12 total authors. However, I was solely responsible for driving the outline and content of the book, even thought I listend (and depended) heavily on my authors to know and write well in their given areas.

Some good books  :

1. Microsoft SharePoint Products and Technologies Resource Kit

2. Building Enterprise Portals with Microsoft Sharepoint Portal Server

3. Microsoft SharePoint Portal Server 2003: Planning, Design & Implementation

4. Microsoft SharePoint Portal Server: Building Knowledge Sharing Applications

5. Microsoft Sharepoint Portal Server 2003 Unleashed

6. Microsoft Sharepoint: Building Office 2003 Solutions