New whitepapers on physical database storage and tempdb...
Below are links to two new whitepapers from the storage engine team. Please check it out to get better understanding of the new features in SQL Server 2005 and enhancements.
Working with TempDB
https://download.microsoft.com/download/4/f/8/4f8f2dc9-a9a7-4b68-98cb-163482c95e0b/WorkingWithTempDB.doc
Physical Database Storage
https://download.microsoft.com/download/4/f/8/4f8f2dc9-a9a7-4b68-98cb-163482c95e0b/PhysDBStor.doc