I have a complete (I hope) list of SharePoint 2007 books here.
None of them are yet released ! (Though many can be pre-ordered from
(But please get your terms right. You are upgrading from SPS 2003 to MOSS
2007 - WSS doesn't come into it.)
There are three upgrade paths. Two are upgrade in site and one relies on you
taking a backup of the database and using this in a new installation.
Microsoft *do* have papers for this installaion not just marketing papers.
You can find links to them by going here
and searching on upgrading - there's also a web cast
WSS FAQ www.wssv3faq.com / wss.collutions.com
No private questions please (additions to FAQ welcome)