Can FSNavigator produce a correct FMC flight plan?

When I produce a Flight Plan in FS Navigator am I safe in assuming that the altitudes noted against the waypoints in the final plan are the ones I should use?. I ask this question because:1. The Plan's altitudes seem to bear no relation to the cruise height I stipulated when building the Plan.2. Presumably these altitudes don't take mountain heights into account.3. After exporting the Plan to the FMC the altitudes differ from the original Plan.In short how can I make sure that the heights in the final FMC Flight Plan are right for that particular flight?Cliff