Dear pbz,
As a DV winner, the right form to use is I-134 if you are ever asked for one. Follow this link for confirmation kabul.usembassy.gov/im_affidativ_support2.html
Thanks for the link loula. I understand I-134 is the right form to use for us (thanks to boabab) although the interview letter says I-864. I was just trying to get a sense of if this comes up at all during the interview process, me being on a F1 as well (like armanio).