Hi, Fishwife (great name!)
Don't worry too much about the different kinds. You will be surprised to find that the moves are very similar in all of them. Some are just more gentle, others geared toward something specific like posture or weight loss. Just start with a beginner's version of something (hopefully general).
Yoga Zone has good DVD's for home. In my area, the cable television company provides an "on demand" service. I think that costs about $4 a month to subscribe, and boy is it worth it. They have a series called Lifestyles & Learning and there are several yoga classes there. You just turn on your TV whenever you want, and yoga is waiting for you. New classes every month so you don't get bored. Most of the yoga is by Yoga Zone.
You can also buy the DVD's through Amazon, or you might try your local library to rent them for free. I have a link to a good starter DVD called AM/PM at the end of my yoga article here:
http://www.bellaonline.com/articles/art11496.asp Good luck, and let us know what you think of it!