No problems at all - projects created in earlier versions of the QSR software can be converted to NVivo 9. To do so, choose File > Open, and select the project you wish to open. A 'Convert Project' dialog box will open - use the Browse button to choose a location and new name for your project. Click Save and then Convert.

Note: Your NVivo 8 project will look slightly different when you open it in NVivo 9. For example, your 'free' and 'tree' nodes, and 'cases', will be converted to 'nodes' (grouped into folders under the 'nodes' folder).