A good article to point out the checksum "issue".
The one tip that I think the community would benefit from is how to ensure the bit is flipped on and that all pages are read (maybe I read through too fast and didn't see the how).
Per Paul Randal (unfortunately don't have a link handy), a DBCC CHECKDB([dbname]) WITH DATA_PURITY should be ran in order to get the checksum fully implemented after the upgrade from SQL 2000.
With that enabled, errors 823, 824, and 825 will be triggered when there is a potential for disk read/write failures, and I have new SQL Agent alerts set up for each of those errors in order to receive those warnings before they become major issues.
The steps I follow when upgrading a DB:
1. Restore the DB to SQL 2005/2008.
2. Change compatibility level to 90 or 100.
3. Change to page verify checksum
4. DBCC CHECKDB with data_purity (to ensure checksum is good to go)
5. DBCC UPDATEUSAGE (as a best practice to get the usage data up-to-date after the upgrade) -- sometimes needed to correct issues found by the data_purity check as well.