I bought an NEC ND 3520A OEM, now I want to know the best configuration:
a. should I leave it with its stock firmware or upgrade the firmware (cause I
read that stock firmware handled media better in the review section) ?
b. I have an ASUS DVD-E6116P1 dvd-rom already and bought an Lite-On it
SOHD 167T dvd-rom which is better compatible with my NEC
burner for transferring data to it ?
Like to hear some advice.
Thanx 
This is asked so much over the time. http://club.cdfreaks.com/showthread.php?t=124863 should help you.
Yo-
Looks like the 1.26 firmware is best - your 3520 should work well with the Lite-On 167 DVD-ROM as a reader/ripper
Can find firmware here:
http://www.micheldeboer.nl/firmware/
Mike
You also might want to remove the riplock on your 167T with firmware from these guys:
Thanks these links are good for the nec 3520a burner thanks a million. 
ttt