Animation methods

Hey, I'm using 3DS max 5 and have a question about animating space ship. Up until now I have been using the Auto Key button to key frame thembut this sometimes creates wierd motions like varied speed and when turning it rotates but then to animate it to go straight on from there I need to use the XY axies but that means it's very hard to make it go in a straight line. I know that animation is possible using path constraints but occasionally the motion is jerky. Any tips?

Thanks in Advance
Rawree