|Why are you starting a new thread? You never finished with the other one.|
Your "new" HD 2600Pro will not be useable on a new system, neither with the RAM. And it's very possible that your power supply won't have the necessary plugs required by new boards & video cards, meaning it will have to be replaced as well. So at the very least, you will need:
- video card
- power supply
Do you have $300-400 to invest in a new build?
I'm guessing that you plan on using your old HDD(s) & optical drive(s)? Modern boards only have one IDE/PATA channel so that means you're limited to just two IDE devices. If you want more than that, you'd either have to install an IDE controller card or upgrade your HDD and/or optical drive to SATA.
Regardless of what you do, Windows will have to be reinstalled. You will NOT be able to run your old Windows installation with a new motherboard.