The good news is that you can use JReviews and Joomla Tags on the same site - as long as you are running the latest versions of each component.

 YOU MUST install JReviews first

Then rename /mambots/system/xajax.system.php to  xajax.system.php.saved

Then rename /mambots/system/xajax.system-mambo.php to  xajax.system-mambo.php.saved

 Then install joomla Tags/Joomla Knowedgebase and follow through the admin screens in that component (This will install the bfFramework version of xajax)

Then both components will work :-)