Hi IJM - I got a Big Foot for my machine
http://sewmamasew.com/blog2/?p=863 you have to know whether your machine is low shank or high shank. You do this by measuring the distance between the bottom of the shank (where the foot attaches) and the base plate. I'm not completely sure but I think a low shank is around a quarter inch, but don't quote me!
Here's a link to the UK site where I got mine - not much use to you I know but good information. And you see that they ask for your make and model to be sure they send you the right foot and adaptor if necessary. Maybe if you google you can find something comparable in the US, or a local sewing machine shop if you have one.
If you can't drop the feed dogs, just tape a thin piece of plastic or card over them. My old machine wouldn't do this. My newer one has a switch just to the right of the bobbin case. I'm assuming you don't have the manual anymore? I didn't have for my old one but I found it online - try googling. :D
Hope this helps! :D
EDITED to say that someone smarter than me knows that low shank is under a half inch not quarter! :oops: :lol: Thanks Dizzy! :D