Calculating Hours, Mins over 24 hour periods

SQL Apprentice Question
Below I'm returning the decimal duration [decDuration], a HH:MM:SS format
without "padding" 0's [realDuration], and a HH:MM:SS format with "padding"
0's [realDuration2].

If you run my EXAMPLE, in RESULTS below you'll see that [decDuration] and
[realDuration] work fine, but [realDuration2] looses 24 hours if a duration
spans over a day.


Can someone help me modify my formula for [realDuration2] so it doesn't
loose 24 hours if a duration is longer than a day?


EXAMPLE **********


declare @dtStartDate datetime, @dtEndDate datetime, @duration as int
set @dtStartDate = '20060314 09:34:11'
set @dtEndDate = '20060315 14:42:53'
set @duration = datediff(s,@dtStartDate,@dtEndDate)


select CONVERT(decimal(10, 6), @duration / 3600.0) AS decDuration,
RTRIM(@duration/3600) + ':' + RTRIM(@duration % 3600/60) + ':' +
RTRIM(@duration % 60) AS realDuration,
CONVERT(varchar,CONVERT(datetime,DATEADD(s,@duration,'19000101' )),108) AS
realDuration2


RESULTS **********


[decDuration] [realDuration] [realDuration2]
------------------------------------------------------------
29.145000 29:8:42 05:08:42



Celko Answers
Why not keep track of total minutes (or seconds, if appropriate) and
let the front end worry about the display format? Tiered architecture
and all that jazz?