javascript countdown clock help please

[Bubblemate]

hay therfe
i am looking for a countdown clock just the minutes and seconds , or just minutes , but i need it to countdown from say 30mins or15 mins n when it gets to 0 it goes back to the original time n then starts counting down again , anyone help?

[lbalance]

just alter an existing script, like this one:
http://dynamicdrive.com/dynamicindex6/countingup.htm

[Bubblemate]

i was wondering if some would do it and i will pay then?