If you are getting an error like:
Error: Script failed (code "ERROR_NEED_MAJOR_UPGRADE_USE_IMP_EXP") when installing "CentralMgmtStore" on ...
When installing Lync 2010, try dropping the "xds" table from your database and letting it cleanly install:
C:\>sqlcmd -S.\RTC
1> DROP DATABASE xds
2> GO
1> QUIT