We've seen no official word on when we'll see a replacement for the Model 990. If I had to guess, it'd be somewhere in 2008, although when in the year it happens is harder to predict - at some point, I'd assume that both the 970 and 990 will be succeeded by HDMI-equipped products, but which will come first is a mystery. I don't know that I'd delay building my system for that if you're close to pulling the trigger.
As for HDMI (sorry in advance for the "unpleasant topic" thread-jack
), I've actually just posted an update to my
HDMI FAQ , under the v1.3 portion, to cover some of the recent discussions on the subject.