I just got my 40D over the summer and it's a great camera. Most likely, the next stop for me will be FF, so I'll be hanging on to the 40D for a while. Both the 50D and 7D look like great cameras in their own right, but there's nothing there that would compel me to upgrade anytime soon.
Just to make sure that FF is what I really want, I'm planning on renting a 5D towards the end of April when I have some time off from work and trying it out in a variety of different situations. Assuming that I definitely decide to go FF, I don't know if I can really justify keeping both a FF body and the 40D, as I'm not a professional and I usually don't find myself shooting anything that the crop body could do better than a FF body. If all else fails, I've got a G11 that I can fall back on. 
Once I've definitely made up my mind about FF, the question will be whether to get a 5D or save for a while longer and get a 5DII. If the 5DII would come down to $2000 or less, either new or used, I'd most likely go that route.
Heather 



