Frames are roadblock for search engines. Very few top-ten ranked sites use frames. Keeping that in mind it’s very difficult to get framed site into the top-ten rankings. Frames increase the file size and the total number of words that make up a web site.
frames = bad this includes bing/yahoo & aol but then, if the frame goes back to another page on your site - that's sorta acceptable, sorta kinda not really
Why do you need to use an iFrame to show up a website? If this is for example an Youtube video and you try to increase the views, I understand, but for a normal website I don't think this is a good idea!