OK, a few more thoughts.

First, why not pick up a component video cable for the Wii?

Second, I agree with AvFan - I've used both DVI/HDMI and component outputs from my cable box and never found a preference. I've used Pace Micro and Scientific Atlanta boxes. You're already planning to run component to the 990 anyway, so this is probably more for your own peace of mind than anything else.

Third, when/if you get a Blu-ray player, I'd assume that it would replace the DVD-F84S. You'll want to use HDMI, though, and you'd have a few options at that point. One would be to move the Xbox to component and use its DVI for the Blu-ray player. Another would be to run straight to the TV. Or you could put an HDMI switch between your sources and the 990, thus expanding the 990's DVI switching. I did the latter for a while with my 990, first using a MonoPrice two-port switch and later with an OPPO Digital HM-31 . I'd probably lean toward doing the first (moving Xbox to component) because it's the simplest, but any of them would work.