Hi rotiron,
I can't presume to give you medical advice as I'm not a health care professional. I understand osteoporosis can be thwarted by weight bearing exercise, as well as plenty of calcium and magnesium. A healthy diet rich in plenty of fruits & vegetables, especially dark green and leafy can be of benefit towards your overall good health. Develop a love affair with broccolli, romaine, spinach etc. (preferably raw)
The effects of osteoporosis are not limited to the spine, however this is one of the areas where it is most noticeable. In terms of exercise, you really want to be exercising all over. Not just the back muscles but all over. osteoporosis can affect the hips, limbs, etc, just as easily as the spine. You will also want to avoid soda and other highly acidic foods. These create such a chronic state of acidosis in our bodies that in an attempt to regain it's proper pH, our bodies will literally leach the calcium out of our bones & teeth.
One of the best low impact exercises you can do in my opinion is swimming. you can get a full body workout including cardio all-in-one.
You might also want to invest in some pH testing strips, and regularly test your bodies pH. This will help you to determine for yourself which foods create an acidic state in your body, and eliminate those foods accordingly.