You are looking to the HD Fury to let you use the HDMI out of your DVR and thus free up the component out for the secondary display, because the display lacks DVI or HDMI, correct? Here are my big concerns, one comping from my experience with HD cable boxes (not HD satellite boxes) and the other from a video switching quandary.
First, my HD cable boxes have all disabled component output once a DVI or HDMI output was connected to a display. Thus using the DVI or HDMI output (I've had both) didn't do anything except kill the component output - if your DVR behaved similarly, the HD Fury would have gained you nothing (except moved the point where video changes from digital to analog to a different point in the signal path, that is). Second, I know that using the 990's DVI switching will make the component switching problematic at best - in fact, I wouldn't even try to use the two in parallel. In that case, you would only be able to connect the DVR's component output straight to the small display and you'd lose any switching benefit from the 990 as well as access to the 990's setup menu (unless you also kept the composite video connection from the 990's monitor out).
I did some googling of your DVR and found a user manual. It took some hunting, but it appears that if you have it operating in "Single Mode" the "TV2" outputs will always be active and will get the same signal as the HD "TV1" output (with HD stations scaled down to 480i). If you can get the DVR to provide a signal via composite in addition to the component output, I think that you can connect that composite to the same input on the 990 that the component is running to and the composite monitor out will still work. I don't have anything connected that way to test it, though. If that doesn't work, you can still connect the composite to the 990 and use the second zone controls to get the video switched through to your display, although at that point you lose access to the 990's menus. I'd leave the second zone scheme as a "fallback" approach, as it may also require a separate connection to the 8" display for using the 990's menu.
With the exception of a couple of copy protection-driven audio limitations (DVD-A and SACD over coaxial/optical), every output on the 980H is active at all times. The component output is limited to 480p for copy protected DVD's, but it, the composite, and the s-video all work all the time.