Thanks, KCK. Figured that was the case.
The notebook is a Dell Inspiron 4000 with Dell's 24X CD-RW/DVD Module. P/N on it is 6P811-A00. Can't tell who the OEM is, but labeled Made in Korea. I've checked with Dell's D/L site - unable to find any firmware updates for this particular drive. The only reason I'd be interested in using MRW on both is that it seems to format a *lot* faster in MRW - as in 15 seconds versus 10 minutes with CD-RW. At least the EasyReader software will let me read and copy from a CD-MRW disc on my notebook so the discs I've already formatted that way on the desktop are not truly wasted, but I'll stick with CD-RW in the future on both.
Thanks again. This is a really good resource forum, thanks to the quick responses from folks like you. I really appreciate it.