The format [h]:mm is the one to use. You could also use [h]:mm:ss, for finer detail. This will also display correctly for larger hours and minute solutions. I think anything over 14 hours will display incorrectly unless you use the format I mention.
It is not a default format so you will need to do a Custom format. Right click a cell, Format Cells/Custom, and then type in as above.
Edit! this is for adding hours
Last edited by Spurlash2; 27th May 2011 at 18:28.
Reason: edit solution!