This may be a nonissue for the OP, but it was a HUGE deal to me, hence my keeping my Oppo DVD player in addition to owning a Toshiba HD-A1 and a PS3:
I assume you have no PAL or non-region-1 DVDs?
If you do, you'll want to keep the Oppo as part of your system. To my knowledge there is no HD-DVD player *or* Blu-Rayer player on the market right now that will upconvert PAL and non-region-1 NTSC SD-DVDs.
One of the areas I focus on in my collecting is music DVDs, and there are boatloads of obscure/niche European and Japanese releases that will likely never find their way to HD disc (or at least not for many years).
"But I want to do community service; I want to teach the handicapped how to yodel." - Hudson Hawk