CV runs 3.5.1. It's nice but I think if you're going to make that drastic of a jump from 3.0.7 to 3.5.1 it might be prudent to back up the database and go from a clean install.
And 3.5.0 is not free. $168.00 to buy, $80.00 a year to lease. The point 1 upgrade is part of the 1 year free upgrades.