That's a lot of questions
Things you will not need
prism card
original motherboard
original cpu
original ram/ps/etc
roms -our stance is that you need to own the original roms. We cannot and will not supply roms with this solution. We have built a ROM reader that will allow nucore users the ability to backup their ROMS.
Good question also about our hardware becoming obsolete.
The main difference is that we will not have a super complex add-in board like the prism card. That is really what stands in the way right now. Our add-in board will be very simple by comparison and if all goes well end-users will be able to repair the board themsleves (if you can't solder you could always send it to clive who does board repair.) Prism boards contain custom components that are no longer available. Ours will contain very common components. Details of the board are not finalized but this is our intention.
We haven't released the minimum pc requirements yet. I will tell you that a dual-core processor is required. The rest of the specs were catered towards the cheapest hardware you can buy today. I spent $375 at circuit city for my test machine and it includes a bunch of things that our solution won't require (dvd drive, card readers, speakers, way more memory than is required, a hard drive)
I hope this helps.