Maybe some descriptive text is needed and/or a rewording of the options.
For example "Only for the currently logged in user" make it seem like no one else will be able to use this particular LiteStep installation.
Whereas "For all users on the computer" sounds more like what people would want, but they may not realize that everyone's shell will automatically become LiteStep.
And the third option sounds like what the 2nd option actually is.
1st Option: Set LiteStep as default system shell for all users. (Only select this if you do not want to enable profile support in the next page)
2nd Option: Set LiteStep as the shell for the current user. (LiteStep may be set as the shell for other users in the future as well)
3rd Option: Do not set LiteStep as the shell at this time. (File installation only, no systems settings will be changed)
Maybe some descriptive text is needed and/or a rewording of the options.