Q:

SharePoint 2007 - 2010 DB Migration

I'm about to perform a DB migration of an Intranet Publishing Site. Is it necessary to create the site collection before performing the DB restore?

A:

To be clearer, you actually only need an Web Application to which you would attach the database. I would highly recomand before doing that go through checking/testing at least by using:

Test-SPContentDatabase which will tell you if you got all other
dependencies installed, etc. (http://technet.microsoft.com/en-us/library/cc263026.aspx)
Run pre-upgrade checker (see here http://technet.microsoft.com/library/cc262231(office.14).aspx)

Also you would need at least MOSS with SP2 to be able to run these commands. There is so much documentation written on the subject. Start here http://technet.microsoft.com/en-us/library/cc262792

