has anyone tried walk aerobics?

Oh yes. Leslie Sansone's Walk Away The Pounds series.

Here is her site:
http://www.lesliesansone.com/

You can see previews of her videos here:
http://www.collagevideo.com/

Then you can buy them much more cheaper here:
www.amazon.com

I started to use them two years ago, as a preparation to a jogging programme.
In ONE month I lost 8 lbs (without any dietary changes), my headache, backache, insominia disappeared. After one month my heart-lung-legs were ready to jog constantly 1 mile, to start a real jog/run programme.

Fortunately, I have Comcast digital cable with on demand and I can watch them anytime I want. I am hooked on them. They are perfect for me to start getting fit.