One problem with that password generator - you only allow 17 total characters (0-9, A-F, hypen) which makes hacking it much simpler than if you allowed 63 or more characters (A-Z, a-z, 0-9, hyphen).  Just as a simple example, a brute force attack on a 4-character password with only 17 allowable characters would take (at maximum), 83,521 attempts.  A brute force attack on a 4-character password with 63 allowable characters requires a maximum of 15,752,961 attempts.  Bute forcing a 4-character password that uses all standard keyboard-accessible printable characters (95 total) requires 81,450,625 max. attempts.

Here's a simple password generator that takes your idea of using NEWID(), but generates significantly stronger passwords with any printable/keyboard accessible characters from SPACE (0x20) to tilde (0x7e).  This may have to be modified to eliminate certain characters if you want or need to exclude them:

/*

-- Requires a numbers table like this

SELECT TOP 500 Num = IDENTITY(INT, 1, 1)

INTO dbo.Numbers

FROM syscolumns s1

CROSS JOIN syscolumns s2

ALTER TABLE dbo.Numbers

ADD CONSTRAINT PK_Numbers

PRIMARY KEY (Num)

*/

-- Set this to the max length for the password to generate

DECLARE @pwd_length INT

SELECT @pwd_length = 255

-- Initialize variables, varbinary work password and varchar final pwd

DECLARE @work_pwd VARBINARY(256)

SET @work_pwd = CAST('' AS VARBINARY(256))

DECLARE @pwd VARCHAR(256)

SET @pwd = ''

-- Use NEWID() to generate somewhat "random" string of bytes

WHILE (DATALENGTH(@work_pwd) < @pwd_length)

 SET @work_pwd = @work_pwd + CAST(NEWID() AS VARBINARY(16))

-- Limit it to the length defined by @pwd_length

SET @work_pwd = SUBSTRING(@work_pwd, 1, @pwd_length)

-- Put it in a table

CREATE TABLE #PwdChars (Num INT PRIMARY KEY NOT NULL, i INT,

 PwdChar INT)

-- We need to account for non-printable and special characters here.  We only want

-- keyboard accessible characters; basically SPACE (0x20) to tilde (0x7e).

INSERT INTO #PwdChars (Num, i, PwdChar)

SELECT n.Num, CAST(SUBSTRING(@work_pwd, n.Num, 1) AS INT),

 CASE

 WHEN CAST(SUBSTRING(@work_pwd, n.Num, 1) AS INT) < 32

  THEN CAST(SUBSTRING(@work_pwd, n.Num, 1) AS INT) + 32

 WHEN CAST(SUBSTRING(@work_pwd, n.Num, 1) AS INT) > 254

  THEN 126

 WHEN CAST(SUBSTRING(@work_pwd, n.Num, 1) AS INT) > 126

  THEN CAST(SUBSTRING(@work_pwd, n.Num, 1) AS INT) / 2

 ELSE CAST(SUBSTRING(@work_pwd, n.Num, 1) AS INT) END

FROM dbo.Numbers n

WHERE n.Num > 0 AND n.Num <= DATALENGTH(@work_pwd)

-- Now loop through and build the character password

WHILE @pwd_length > 0

BEGIN

 SET @pwd = @pwd + CHAR(

  (SELECT PwdChar

  FROM #PwdChars

  WHERE Num = @pwd_length))

 SET @pwd_length = @pwd_length - 1

END

-- Clean up

DROP TABLE #PwdChars

-- Display it

SELECT @pwd