How to Split String based on Space

;WITH c AS
(
    SELECT 'Marilyn Kean Kirkland' AS legalname
    UNION ALL SELECT 'J Smith' AS legalname
)
SELECT
    SUBSTRING(legalname,1,space1) firstname,
    SUBSTRING(legalname,space1,space2 - space1 + 1) middlename,
    SUBSTRING(legalname,space2 + 1,totallength - space2) lastname
FROM
(
    SELECT
        legalname,
        CHARINDEX(' ',legalname) space1,
        LEN(legalname) - CHARINDEX(' ',REVERSE(legalname)) space2,
        LEN(legalname) as totallength
    FROM c
)c
GO