So the one stupid thing I did when I was migrating was I deleted my Community Server tables and site before installing Graffiti.  I did back them up by exporting them to my local machine first, so the first thing I'd advise is that Graffiti uses separate table names and so if you don't want to delete CS straight away you don't have to.

That said, you probably only need the cs_Posts table for the migration, and I'd advise if you can start a new SQL db or move your CS SQL db, to do so - so you start with a clean install.

From there what you want to do is grab the migrator tool from @Jaymed at Telligent.  At the moment it only works with Community Server 2007, so if you want to migrate your posts you may want to upgrade if possible.

Jayme linked me to his migrator at: http://ndepth.net/blog/graffiti-beta-is-launched/

Once you have placed in your server connection string, the name of your blog into the "Application Key" (ie if your blog is at "<site>/blogs/myblog" then myblog is the key) and your UserName, hit the Get Data button and it will give you a list of posts to import.

Great thing is, it imports all your comments too!

After you've done that, you can grab Rich Mercer's redirection plugin from here: http://richmercer.com/graffiti-plugins/

That will migrate your blog from a Community Server install to the Graffiti CMS and keep all your trackbacks and links from other sites active and works perfectly!

You can repeat the Migration for each user on your CS install if you want them all brought across to Graffiti - just make sure you have them set up as users of your Graffiti site, and set up new Categories for each separate blog before you do and the Migrator tool will give you the option of which Username and Category to import the posts into.

The only posts of mine it didn't import was a couple that had the same post title in Community Server and so created unique index issues in Graffiti, and they were solved by changing them back on the Community Server site, or not important enough to bother with anyway.

All in all pretty painless, so thanks to @richmercer and @jaymed for all your help fellas and for providing the tools even at a beta stage that means that we can be up and running straight away.

Seriously Graffiti is one of the easiest and best installs I've ever had to do :)