The method you use to accomplish this will depend on how the date and
time information is stored. Excel can store< information one way and
present< it in another. An Excel compliant date is in fact a large
integer number: today, 10 Feb 2010, is stored as the integer 40219. An
Excel compliant time is a fraction of a day: 6:15 pm is stored as a
decimal portion of a day, or 0.760417.

Test how the data is stored by reformatting the columns as numbers and
expanding the decimal points. This will show if the data is stored in
an Excel compliant format.

If your date column and your time column are both stored as Excel
compliant, you should be able to use =A1+B1 (substituting your cell
references, of course) to achieve your desired output.

If the dates and times are stored as text it can still be done but it
takes some doing. Post to this group with your formatting results
along with some examples if you still run into problems.

Dave O
Eschew obfuscation