Is the following correct?

select * from ABXDB01.mgd_req_holdg where ABX_REQ_BUCKT = 'OK' where
(CMPL_Q_DT >#12/5/2007 5:00:00#)

No.

(a) SQL Server does not use # to delimit dates;
(b) you should never use m/d/y or d/m/y or whatever that is (the fact that I
can't tell if that is Dec. 5th or May 12th should be a clue!);
(c) you can't say WHERE twice;
(d) you should always list your columns and never use * in production code.

SELECT <column_list>
FROM ABXDB01.mgd_req_holdg
WHERE ABX_REQ_BUCKT = 'OK'
AND CMPL_Q_DT > '2007-12-05T05:00:00';

select * from ABXDB01.mgd_req_holdg where ABX_REQ_BUCKT = 'OK' where
(CMPL_Q_DT Between #12/2/2007# And #1/1/2008#)

In addition to points above, which apply again, I strongly recommend NOT
using BETWEEN for date range queries.  The problem is, do you want to
include rows from January 1st at 12:00 AM exactly (or that were entered
without a time)?  What about rows from January 1st at 12:01 AM?  12:05 AM?
4:00 AM?  Your query will leave those out.  How about:

-- if you don't want to include any data from 2008:
SELECT <column_list>
FROM ABXDB01.mgd_req_holdg
WHERE ABX_REQ_BUCKT = 'OK'
AND CMPL_Q_DT >= '20071202
AND CMPL_Q_DT < '20080101';

-- if you do want to include data from 2008-01-01:
SELECT <column_list>
FROM ABXDB01.mgd_req_holdg
WHERE ABX_REQ_BUCKT = 'OK'
AND CMPL_Q_DT >= '20071202
AND CMPL_Q_DT < '20080102';

For more info on date range searching see Tibor's article:
http://www.karaszi.com/SQLServer/info_datetime.asp

The # sound is used in SQL the same as the "*" is used in DOS.

I have no idea what you mean.  It looks like you are borrowing code from
Access, not DOS.  In SQL Server, # is not used for delimiting dates.  % is
the wildcard character representing any number of characters, not * like in
Access.  And for single characters, it is an underscore _ not ? like in
Access.