Find fulltext indexes in SQL Server 2008
To find a list of tables that have a FULLTEXT INDEX:

SELECT
    SCHEMA_NAME(t.schema_id) AS SchemaName,
    t.name AS TableName, 
    c.name AS FTCatalogName ,
    f.name AS FileGroupName,
    i.name AS UniqueIdxName,
    cl.name AS ColumnName
FROM 
    sys.tables t 
INNER JOIN 
    sys.fulltext_indexes fi 
ON 
    t.[object_id] = fi.[object_id] 
INNER JOIN 
    sys.fulltext_index_columns ic
ON 
    ic.[object_id] = t.[object_id]
INNER JOIN
    sys.columns cl
ON 
    ic.column_id = cl.column_id
    AND ic.[object_id] = cl.[object_id]
INNER JOIN 
    sys.fulltext_catalogs c 
ON 
    fi.fulltext_catalog_id = c.fulltext_catalog_id
INNER JOIN 
    sys.filegroups f
ON
    fi.data_space_id = f.data_space_id
INNER JOIN 
    sys.indexes i
ON 
    fi.unique_index_id = i.index_id
    AND fi.[object_id] = i.[object_id];


To enable and disable a FULLTEXT INDEX refer msdn

sp_fulltext_table 
   [ @tabname= ] 'qualified_table_name'         
   , [ @action= ] 'action' 
   [ 
   , [ @ftcat= ] 'fulltext_catalog_name'         
   , [ @keyname= ] 'unique_index_name' 
   ]


The preferred method is to use ALTER FULLTEXT INDEX [myFTindex] {ENABLE/DISABLE} instead of the deprecated sp_fulltext_table.