long term strategy

I have been lucky enough to be in a seemingly sleepy series of meetings with a camera *DVX then HVX) where it turns out history is unfolding. So has my knowledge of the craft, not my original calling in life. It's been a slow learning curve! I am no at a point where the stakes on the material are higher. One piece I made has travelled through legislative halls and have had offers by several people to broker my next piece to the big league if I want, which isn't exactly my first priorty, but it has gotten me contemplating format issues...

Questions: I am on a limited budget. I have a DVX and an HVX and about 7TB on firewire drives right now. I have been using both cameras 24p SD setting, after initially using 30p in the DVX because I liked the picture. Will this render this footage unusable for, say, PBS purposes, or even film out later?

Do I HAVE to go to HD in this day and age? If so, does that mean the last 3 years of tape are useless?

I have to 16GB cards and a firestore drive, but this footage is so important twenty-five years from now and six months from now that I don't want to take any chances with some sort of crash. I have had hard drives fail already.

I have about 20k I can invest in equipment over the next couple of months. I have to have two cameras for one shoot I do every month. If I go HD that means another HVX and some 32 G cards.

Can you Elders help me out with this?

Thank you, by the way, for all that you give the hungry and thirsty who show up at this site. I have been floating around for a couple of years, now, reading and absorbing as I can (usually in some crisis!) and I very much appreciate the gifts you give us...