MS Excel - Concatenating Date and Time Values

I have a date field value as 20/09/2007 and a time field value as 10:15. I want to combine these 2 values in one cell - 20/09/2007 10:15.
How do I do this in Excel?
Plz help.
TIA.
[206 byte] By [smoluk] at [2007-11-20 11:18:46]