Paul -

You can USE the dynamic components I've built in the latest free version - but you cannot CREATE the components (unless you can write Ruby scripts).

To get full functionality from SketchUp I purchased a license of the Pro version a few updates back... and now I just pay a mild upgrade fee when good stuff gets changed.

For ~$500 (and often times you'll be able to find specials - at AIA events building trade shows like Build Bostons and such) you get a really powerful visualization package. Its not perfect for drafting - but I'm developing ways to work with it to detail a frame + enclosure + schematic designs of whole building. So far so good.

You can do most things with the free version - but Pro gives you some more options for import / export, as well as the power to create the dynamic components... and you also get Layout - which is a page layout program that integrates with SketchUp for creating presentations and 2d drawings - from plans to sections to rendered images... add in Clark's TF Rubies - and you have a very capable CAD package for timber framers... (or furniture builders...)