Nero 7 does work on Windows 7 RTM, I installed it the other day
Have you tried re-installing Nero then uninstalling again to see if the install gets to 100%?

Note
You may need to run the installer with Compatability for Vista but you shouldn't really have to
The best thing if that fails is to run
regedit by typing it into the start menu and search the registry for ALL entries pertaining to Nero.

Warning
Don't just delete everything, there are some other entries that have nero within the title so read everything before deleting
Then, do an explorer search for nero & delete the folders relating to 'Ahead' or 'Nero'.