I do not think anyone can guarantee that any motherboard will work with the video card that you have. My theory is that your current motherboard is 2 years older than the one that you are looking at and that may be part of the reason why it does not support that video card. It is possible that flashing the bios could fix the motherboard but it is a risk and it is unlikely that there is an update that would fix this problem.
I hope you didn't spend too much on that Sapphire. You are dealing with rather old technology and it still may not work as well as you would like. Also the motherboard that you are looking at won't support your old CPU unless you are planning on buying a new CPU too. I was in a similar situation recently and it was more cost effective to build a new PC rather than trying to upgrade my old one.