Dave-
Thanks for all your useful advice.
Do you know if a new 27" iMac in Target Display mode can export the iMac's keyboard or mouse signals through its USB ports so the iMac keyboard or mouse can be used to control the external PC that is displayed on the iMac?
Maybe more important (assuming that the answer at this point is no), do you have an educated guess as to whether this is a hardware issue or a software/firmware issue? I would very much like to use a 27" iMac as the monitor for my office PC, but I have delayed purchasing the iMac both ℹ because of the challenge of identifying and installing a compatible Mini-Display-Port video card and (ii) because I don't want to have to use two sets of mice and keyboards, at least not indefinitely. I could live with two mice and keyboards for now, but it would be very frustrating to be unable to upgrade my iMac when Apple does address this issue. Thus my question as to whether this a software/firmware issue, i.e. one that could be addressed through a software/firmware upgrade once Apple gets around to it. If that were the case then I would deal with the video card issue and buy the iMac, but otherwise I am on hold for now.
Thanks again for all your posts.
-JAFDC