In short, here are a couple of possibilities:
You can either use Conditional formatting if you have at least FileMaker 11
Or you can use hidden tabs, with an onObjectModify script trigger:
In your script, you probably won't need to use the "Enter Browse Mode" or put "Enter Browse Mode" before the "Go to Field".
And your script appears to go to the wrong field as I would not expect the next field to be Company Name if the selected type is "Personal".