Those are both really nice upconverters but, for that price, why not just go with the Toshiba HD-A3? It works as an excellent upconverter and you can also watch HD DVD's. The only drawback to the ToshibaHD-A3 is that it doesn't support DivX. I don't know if you're here in the states but, Circuit City has them for 100 dollars right now, darn good buy!
Update: Ahhh, didn't notice that you mentioned it was used. As I said, those are both nice players, I guess really price would play a big determining factor. If I had to choose between the two, I'd go with the DV-970HD because it has HDMI opposed to DVI. Also, looks like the older model doesn't have the memory card slot or a usb port.
They are NOT selling the ToshibaHD Dvd Player for $100.00.
I went ther online and it is $149.95.
I called a Representative that said those might be In Store
Promotions she did not know. So If you think you are going to
get One online for $100.00 You will not.
Just wanted to let everyone know because I don't have a Circuit City in my town and got excited over nothing.