I found it, it's in the Firewall snap in (mmc)

"John Lee" <lejohn@email.unc.edu> wrote in message
news:%23T10NdgGHHA.2112@TK2MSFTNGP03.phx.gbl...
> How can I turn on "allow incoming echo request "on Vista so I can ping it
> from another machine?
>
> Thanks.
>