Want some help building and deploying site definitions, complete with resources like Web Parts, CSS files, etc.?  Get thee to http://workspaces.gotdotnet.com/sharepointdevkickstart, the latest in our never-ending effort to plug information gaps in the SDK.  A corresponding whitepaper should surface soon on MSDN, but this code will help you all by itself.  We (i.e., those of us involved with SharePoint Products and Technologies developer evangelism, plus those who work with us closely, in this case our friends at Interlink) opted to put in on GotDotNet rather than MSDN so it could evolve as a community workspace.