I just purchased and installed a new Samsung 348B combo driver this past weekend. It is the retail version w/ 8 meg of cache. It came with firmware T504, just for some background info. I uninstalled Nero and installed the EZCD 5 basic that came with the drive. I downloaded and installed the upgrades and all seemed well. EZCD 5 recognized my drive and I was able to burn, but not at 48X, only 40X (used verbatim 48X and fuji 48X so I know it wasn't the media). So, I updated the firmware to T505. The update went well, or so I thought. After the update, I could only burn at 32X, no matter what media I used. So, I uninstalled EZCD 5 and reinstalled Nero. It said that the 348B was a 40X burner. Unacceptable! The auto-update program from Samsung said I had the latest firmware available. Well, I went to the firmware page and they had T506 as the newest. I installed it and now Nero states the I have a 48X burner! I tested it with Fuji and Verbatim, 48X for both of them.
So, for all of you Samsung 348B owners, check out the firmware page website and use the T506 firmware. Much improved.
Here's the link to the firmware page: http://forum.rpc1.org/portal.php