I haven't programmed in VB, therefore I cant give you the exact syntax. but I'll tell you what to do then you can do it in VB.
Add a timer control. Declare a global variable, lets say Counter and initialize it to 60. Then in the timer tick event; I belive in VB it will look something like Private Sub Timer1_Timer() decrement Counter by one (this will make it count down from 60 at each timer tick event). At the same time set the textbox's text property to Counter. Have a check inside the tick event handler to check the value of Counter, When it reaches 0 stop the timer and launch the new window.
EDIT : Didnt see xcorect's post..., he has given the complete code.. LOL..