Not sure if i follow your requirements, but are you wanting the form to update the spreadsheet and move you to the next field?
In that case, you'll need to use the exit event. If the user presses return, uses tab or the mouse to move to another field, this event is called. So put the cell = textbox code into that event. It should tab automatically to the next field.
Double click your text box in design mode and select the event exit. Type in the:
Activeworkbook.sheets(1).cells(1,1).value = userform1.textbox1.value
provide by lambuhere and robert's your father's brother.
This would be a lot easier with control arrays by the way. Anyone know how to dupe them in VBA.