How do you update your CD/DVD drives firmware?

Ok, here's my drive (I think):
nec dvd_rw ND-2500A
driver date - 01/07/2001
version - 5.1.2535.0

I need to update it because I can't seem to burn any data discs, on DVD-R's anymore, i've tried all sorts of brands and it can't even read them, it just knows they are blank CD's.

Where do I go about downloading a firmware update installer, or something? Can someone point me to the exact one? I've tired searching, but i'm not sure, i've read you've gotta be careful too? As you can render it completely useless if you mess up??

Thanks.