A JOIN is preferred over the older-style WHERE clause, although with an INNER JOIN they should function the same either way:
INSERT INTO myTable
(ID,someData,someData2)
SELECT
tempTable.matchID as ID, myTable.someData, myTable.someData2
FROM myTable
INNER JOIN tempTable ON myTable.ID = tempTable.ID
SQL DBA,SQL Server MVP(07, 08, 09) A socialist is someone who will give you the shirt off *someone else's* back.