exploding string

[mjh]

I could really use some guidance here with PHP and maybe Javascript (sorry).

I want to get the number of mins (eg 115) from a time formatted 01:55:00 (for 1 hour 55 mins duration)

I have used Explode before in PHP to get the 'bits' and then do the math.

HOWEVER, this time i want to show the answer as the user 'tabs' down the form, this sort of thing:

Distance [textbox] miles
Duration [textbox] 00:00:00 format
Pace [textbox] calced pace in mins per miles

I guess this is turning into a Javascript question (sorry)

matt