Thanks for your prompt response. Unfortunately, I use automated installs of WP and I have no familiarity with PHP at all. Even trying to follow the instructions, I already hit a head-scratching dead end when the instructions say "Create a database for WordPress MU on your web server".
Create a database? Like what sort of database?
Do you believe this solution will allow me to say, for example, have a simple WP theme with one menu pointing to 1 blog, and another menu option linked to a second blog?
If it requires a lot of back-end command line tweaking, I think I might be better off creating 2 identical looking sites but have one menu option link to the second site (perhaps on a subdomain which I can handle) with a blog on a different page so it appears to be in a different menu...