Nancy: I think you asked this question in a comment on a photo in the Gallery. I replied there but I'm guessing you didn't spot it. Here's what I wrote:
My advice (for what it's worth) would be to choose a zoom if you want to do both portraits and wildlife photography - especially the latter. With a prime lens, you have to rely on being the right distance (more or less) from the subject to get the perfect shot, which is not always possible with wildlife. Also, the kind of long lens that is ideal for wildlife would not be appropriate for portrait photography, which is usually better suited to a short telephoto (about the equivalent to a 135mm lens on a 35mm film SLR).
If you want Image Stabilization, then your hubby is going to have to go for a Canon lens (and be prepared to sell a kidney - the Canon EF 70-200mm IS USM retails for around $1300), but another option is to go for the combination of a Tamron or Sigma lens and a good tripod. I own a Tamron AF 18-200mm zoom (
Tamron AF 18-200 mm F3.5 - F6.3 Di-II: Digital Photography Review) and it's rarely off my camera. It's also considerably more affordable - around $480.
Telephoto zooms in general are not appreciably poorer quality than primes other than at their extremes (maximum focal length and maximum aperture).
Hope this helps a bit.