partial restore of the database

we r using sql server 2000.wrongly we have updated 26,500 rows instead of 1 row. we have a backup for that database.
how to restore the database up to a particular point as we have updated some 400 rows with correct data. now we want to restore the database for only 26,000 rows.

please any body help us.

If the db is in full recovery model, may log backup with no_truncate option. Then restore db from full backup to another name, apply log and stop at the point before running update statement.