>> I am setting up an Endpoint Protection Manager server (currently a single server) and am trying to figure out the purpose of the LiveUpdate Administrator.
If you install SEPM and you need to distribute updates/definitions for SEP clients only then you don't need to install LUA as it is going to do the same job as your SEPM.
Thumbs up for Prachand who gave reasonable cases when LUA may be necessary. I can add one document more:
LiveUpdate Administrator's Guide
ftp://ftp.symantec.com/public/english_us_canada/liveupdate/luadmin.pdf
so that you can try LUA if you really need it.