I have wanted to get the Tanita scales myself as well. From everything I've learnt, it seems that they always show a higher reading than you would get from a caliper test for example. A good friend of mine has the scales and I was really happy with my reading of a high fat percentage since it meant that theoretically I could lose more.

But like the good advice already given concentrate not on the actual number but the change over time. Use one method and stick to it - it will show progress.

As for calculating lean mass, how much you can lose to be at 20% etc - I know all about that , it drove me nuts

The truth is everything is usually an approximation - every body is totally unique and has its own set of rules and will never follow the standards to the T. So don't worry about that calculation - first of all, when you lose weight, you will also lose some lean mass - that's unavoidable - it will never be 100% totally and purely fat. As long as its mostly fat you are losing, you will be in good shape and find that you can go down well beyond 160lbs and have a reading of 20% or more.

Secondly, the best way to really judge how much fat you stand to lose is taking a good critical look at yourself in the mirror and taking your measurements with a tape measure! You say you've always been buxom (having full hips etc) - so have I! I know all about that - and the plain truth is I carry a lot of fat in that area. I will know that I am in good shape and have attained my goal weight when my butt is not all over the place and I feel good about not having to hide it under over-sized T shirts. What weight will that be at? Who cares! Weight is just a guide-line afterall. You will KNOW it when your body looks great and fit and that's when you know you've reached goal.

As a side note, beware of becoming too critical as well. After months of eating healthy, exercising and assessing ourselves in the mirror its easy to forget to pat oursleves on the back for a good job done and become too focused on a certain weight or a certain "look" we want in the mirror. Best advice is keep in mind how far you've come and don't forget to thank yourself everday that you are giving your body a new and healthy life

Best of luck!