Content database sizing guidance for SharePoint 2010
I ran across this information on http://technet.microsoft.com/en-us/library/cc262787.aspx about content database sizing for SharePoint 2010. This new guidance for SP 2010 has changed from MOSS 2007/WSS 3.0. I had to read it a couple of times to see what it is saying but here is my interpretation of it:
Basically, if you have more than one site collection in the database, stay under 100GB. If you only have 1 site collection in the database and are using it for collaboration, you can go up to 200GB. You can go up to 1TB if that content is not for active collaboration and is primarily read-only content(e.g. Records Center).