I tried, and it did not work! The incremental update function is broken, eventually leading to an "MsiStart.exe had a problem ..." screen. Maybe Nero doesn't have the incremental updates in place yet. Regardless of the reason, it's a shoddy job by Nero.
I then downloaded the 100MB update file. Running the update resulted in a message that I needed to uninstall my older version 7 trial version. I have a registered retail box version 7, not a trial version, and the serial number shows in the Nero Product Center of the retail box version. Once again, a shoddy job by Nero.
So, I uninstalled my version 7 retail box product and installed the update. The update installed, but, when I directed Nero to install to my "E:" partition, rather than the "C:" partition it defaults to, Nero insisted on installing to a "...Nero\Nero 7\Nero 7\..." folder, i.e., no matter what I did, Nero's install insisted on adding a duplicate and embedded Nero 7 folder, no matter where I tried to direct the program to install. The duplicate Nero 7 folder did not appear until I requested that Nero install to something other than the "C:" partition.
Eventually, I decided to live with the extra Nero folder. After the install, the Nero 7 "update" picked up my serial number, but insisted on calling itself a trial version. At that point, I gave up, and reverted to the original retail box version of Nero 7.
Don't get me wrong, I'm a Nero and Nero 7 fan, but Nero needs to take greater care to prevent these annoying glitches from happening.