Excel should be treating the time you past in as a date. If you add one to a
date, you are adding a day:

Jan-01-2009 + 1 = Jan-02-2009

There are 24*60*60 seconds in a day. So, to add just one second, you need
to add a much smaller amount:

TimeNow = StartTime + 1# / 24# / 60# / 60#

Of course, you need to format that column as a time (something like HH:MN:SS)

HTH,

Eric