Pda or smartphone ?

Hi all, just registered.

I now have an O2 Exec and a Nokia N70 smartphone but dont know which one to install sat nav on .
I will probably go with TomTom Navigator (for PDA ) or Mobile 5 for N70.

The decission is: The phone is small and portable with a small screen and the Exec has a lovely big screen but the ubit is a bit of a brick !
Do any of you have experience of sat nav on phone and pda ?

Many thanks,

[Stevie]

Just replied to your PM.