If you've tried, then you probably had a bit of an "ARGH!" moment when you got this:
The first thing you might do is go look for the slipstream installer containing MOSS 2007 + SP1. You'll have another "ARGH!" moment because it doesn't exist yet. Have no fear, you can still install MOSS 2007 on Windows Server 2008 RC1. Ben Curry has the magic recipe for Installing SharePoint Server 2007 on Windows Server 2008 RC1. I just tired it. Worked like a charm!