You don't mention what OS you are using...
In Windows 2000, and possibly XP, You "may" find the plugins here:
Documents and Settings\Administrator\Application Data\Real
(substitute username for Administrator if you are logging in as a User)
In Win 9x you might want to look in a similar "Application Data" folder - sorry I don't have a Win9x machine handy to check.
I'm afraid I'm not completely sure of the above info as I don't allow Real to update at will on my machines
Failing the above you may want to send an e-mail to their customer support folks - believe it or not they will actually respond, I tried it once and was mildly amazed that I received a reply that was "almost" helpful.
Check this page for info on contacting them:
(watch the wrod wrap)
Sorry I can't be any more help than that.