Multiple checkboxes with only one checked allowed.

Hello,

I'm having a problem with a form, and i'm hoping that someone here can help me.

I have 2 sets of checkboxes, each containing 3 different options that can be checked.
One is alligned horizontally and the other vertically.

Something like this.

John [ ]
Paul [ ]
George [x]

and

John [ ] Paul [ ] George [x]

I want (for both sets of checkboxes) that only one of the checkboxes (in this example George)
can be checked.

If for example Paul is "checked" the checkmark for George has to disappear.

Is there a simple way to do this ?
(I'm using Acrobat Professional 8.)

Thanks :-)

Frits