When upgrading from SQL 2000 to SQL 2005 workgroup there's a couple of things you should read up ahead of time… the first being the "official" upgrade guide. the second is the "Susan" version of the document that just covers the needed steps for upgrading SQL 2000 to SQL 2005.
Extracting the XML files using the 'cab' method is much easier than typing in the command to extract (the first time I did it I obviously typed in the command wrong).
But if you are planning an upgrade, print out both documents 'and' the KBs and you'll be in good shape for the upgrade… uh…. just don't follow my lead and lock your car/office keys in the server room…that's not exactly a best practice I'd recommend to follow….