My ISP tech support staff have just confirmed my suspicion that my database's compatibility level is 80; it was originally built on SQL Server 2000. If I read your suggestion correctly, I can change the compatibility level merely by changing the number and then doing another backup and restore?? This seems too good to be true. I'll have to do some more research on this issue.

Your point about being unable to restore a 2008 database from a 2005 backup is true but I'm not sure it's relevant; I would never try to restore the production database (2005) from the test site database (possibly 2008). If I had to restore the production database I'd use the ISP's latest backup (SQL 2005). The purpose of the test site is to allow me to check out new functionality, and test and document upgrade procedures before doing them on the production site, it isn't a formal backup from which I could restore. My real question is, can I run a SQL database with a compatibility level of 80 in a SQL Server 2008 Express server, for testing purposes only? All I'm really doing is supporting a DotNetNuke 4.9.5 site.