If it was that easy, there probably not be NetPros! Jokes aside... you can not. You can export quite a bit of information in 5.x, 6.x, 7.x, but can not import to another version. You would need to massage the data in each CSV file to make it work.
Also, in 8.5 (possibly 8.0) you can get almost everything import/export and move it from system to system. I have to run a few more test, but it exports just about everything and can import just about everything to another system. (pending matching up fields, etc)
