A new feature has been added to Notes 8.0.2 that allows customers to install the 8.0.2 Notes Standard client, but launch the Basic client based on a Notes.ini parameter UseBasicNotes=1.  This notes.ini parameter will allow external programs that launch notes, such as a MailTo: URL, or launching an NSF file directly, to launch notes in Basic mode if UseBasicNotes=1 is set in the Notes.ini.  This will allow customers to rollout a single package, but define which users will launch Basic vs Standard via this notes.ini parameter.  For example, if a machine does not meet the hardware requirements of 8.0.2 Standard, but does for Basic, this will allow the client to launch in Basic mode until hardware has been upgraded,  By default, this parameter is not in the notes.ini and will launch the Standard client if it is omitted or set to 0.  Notes.ini parameters can be pushed out via administrative policy, which make it easier for customers to centrally control this feature.

(The part above is from Ed Brills Blog.)

You can also create a shortcut to start the Notes client and add one of the following switches -sa or -basic.

For example: C:\Program Files\Lotus\Notes\notes.exe -sa. 

If you use a multiuser installation please have a look on technote 1318037.