Thanks for the reply Steve.

It appears sp_helpdb returns the "allocated" size, just like the sysfiles table. I've never peeked at the backup tables, I can do that, but it just seems like there's got to be a better way.

I love the .NET SMO libraries that come with 2005, but under the hood that must use sp_spaceused since the results are inaccurate for my 2000 boxes (until I run dbcc updateusage).