Re: Upgrading from regular WP to BuddyPress
Just to clarify, BuddyPress is a plugin which works on regular WP or WPMU. You can disable and enable all or any part of it at anytime; so if you decide it’s not for you, it doesn’t wreck your site.
If you install BuddyPress 1.2 right from the plugin installer, and switch to the default theme, you’ll have a full-featured BuddyPress up-and-running on your existing site. Then you can play around and work on integrating the new BuddyPress pages into your theme (there are growing numbers of threads and documentation on how to do this).
I’d suggest testing and developing BuddyPress on a test version of your site, not the live one Also as a FYI, you can test BuddyPress at http://testbp.org/.