Isn't the most obviously needed peice of information to diagnose this problem the OS and burning Software versions? But thankfully, I know the speed of your RAM.
Based on the information you gave us, I'd say it's your crappy OS (just guessing since I don't know what you are using) or your crappy burning software (just guessing since I don't know what you are using).
Upgrade to a decent OS such as Linux, Mac OS X, or if you have to XP or 2000
and a decent burning app such as that Record Max something (trying to be non-specific so Xeero can provide a more detailed followup to my rambling unspecific post
Technically, your DVD-R drive shouldn't use any memory, but your burning software will use some.