(this is as an addendum to the above post)
Many, MANY, people diagnosed with CFS in reality have Lyme Disease. Look into this at lyme.org or anything not Yale or Stonybrook, especially if you live in the New England area. I can't back this up with a statistic, but many people I know who were initially diagnosed with CFS in actuallity had Lyme. They spent years sick before they found out. One cautionary note: don't be supprized if your doctor refuses to even test you for Lyme, or if you get a false negative, or if you get a positive and your doctor tells you it's a false positive. It's all part of the crap surounding Lyme today, thanks mostly to Yale University and some corporations.