Actually ... I think you can go from 2.2.9 to 3.0 ... but it could be other minor tweeks in the actual data itself ...
If you're putting it off because you've never upgraded before, then don't worry about it ... I was in the same boat the other day when I went from 2.2.6 to 2.3.0 to 3.0.0b3 ... the updating process from 2.2.6 to 2.3.0 was extremely short and simple !!!
Anyhow ... obviously I'm no expert and someone can give you a better answer ... lol .. I just wanted to let you know that you can upgrade from 2.2.9 if that's what you're running !!!