For SQL server 2000 : i wrote this script
-- full search and replace version sql server 2000
SET NOCOUNT ON
DECLARE @columnname varchar(255), @tablename varchar(255), @sql varchar(8000), @oldvalue varchar(1000), @newvalue varchar(1000)
SET @oldvalue = 'OldText' -- text to replace
SET @newvalue = 'NewText' -- text to replace by
DECLARE table_cursor CURSOR FOR
select name from sysobjects where xtype='U' AND [name] LIKE 'MyTablePrefix_%' -- your table prefix
OPEN table_cursor
FETCH NEXT FROM table_cursor
INTO @tablename
WHILE @@FETCH_STATUS = 0
BEGIN
PRINT 'Updating Table: ' + @tablename + '...'
DECLARE column_cursor CURSOR FOR
SELECT syscolumns.name AS column_name
FROM sysobjects INNER JOIN
syscolumns ON sysobjects.id = syscolumns.id INNER JOIN
systypes ON syscolumns.xtype = systypes.xtype
WHERE (sysobjects.xtype = 'U')
AND systypes.[name] IN ('varchar','nvarchar','text','ntext')
AND sysobjects.name = @tablename
ORDER BY sysobjects.name, syscolumns.colid
OPEN column_cursor
FETCH NEXT FROM column_cursor INTO @columnname
WHILE @@FETCH_STATUS = 0
BEGIN
PRINT 'Updating Column: ' + @columnname + '...'
SET @SQL = 'UPDATE ' + @tablename
SET @SQL = @SQL + ' SET ' + @columnname + ' = Replace(CAST(' + @columnname + ' AS nvarchar(4000)),'''+ @oldvalue + ''',''' + @newvalue + ''')'
--PRINT @sql
EXECUTE(@SQL)
FETCH NEXT FROM column_cursor INTO @columnname
END
CLOSE column_cursor
DEALLOCATE column_cursor
FETCH NEXT FROM table_cursor
INTO @tablename
END
CLOSE table_cursor
DEALLOCATE table_cursor
Run it during the night as it take quite a while to run on medium to big databases...