nightstalkerpoet, I recommend investing in a BluRay player that upconverts DVDs. I know that's not what you're looking for, but hear me out.
Software upconversion is a permanent change. It will introduce artifacts that are not present in the DVD9 and you'll be stuck with them. Five years from now, your new 60" LED flatscreen will reveal every little defect. On the other hand, five years from now, a new player will upconvert that DVD9 much better than any software could today.
In short, stick with the DVD9, and let future hardware advancements do the heavy-lifting.
Just my two cents.