I would suggest you purchase the number of points you think you will need for the next vacation. If you believe it to be 160 pts, then that's what I would suggest you purchase. Since this would be fairly new to you, it's best to know how you vacation with
DVC, since, if you are anything like many of us DVCers are different from our pre DVC days.(Before we purchase DVC, we
tried to go to Disney every year. But after we purchased, we were completely addicted and had to go once a year, but then that wasn't enough so we bought more points and now we have to go twice a year...

It is just a very different way to vacation. And it may be something that you love or not, either way, I think you need to experience it first to purchase more points that you presently require.)
Once you are comfortable in DVC and you are sure you will need more points, then that's when you should purchase it. Again, if you are anything like us, you will be adding on in a year or two. It's just very addictive. Now, some are not as Disney obsessed and are fine going to Disney once every two years and if you find that every two years is good for you, then as you already mentioned 160 pts is enough for you. Then you don't have to worry about using up the points without losing them.
Another suggestion is if you like the price now and feel that you want to purchase alot of points now, you can purchase 160pts in one contract and purchase a smaller contract to go along with it (ie. 40pts to make your total 200pts). Then if for some reason you feel that 160 pts is all you need, you can sell your smaller contract with ease.
Just some suggestions. Good Luck.
