That's useful to know, since I would like, eventually, to upgrade the site to DNN 5.X. I'll obviously have to upgrade the database then. I'm still torn whether to go with SQL 2008 or 2005 (using the x86 binaries) on my 64-bit laptop...
I don't have access on the ISP site that would allow me to do your upgrade compatibility-backup-restore sequence - the ISP staff do the backups for me (their rule) and I suspect they'd also have to do the restores.
This has all been VERY helpful and informative, and I thank you for taking the time to work through it with me! Happy New Year!
Nature bats last.