5V is 5V is 5V. The adapters are compatible. The amp rating refers to the peak amount of power you can get from the adapter. The actual amount of power flowing throught the adapter is determined solely by Ohm\'s law.
In short, it never hurts to have an adapter that can supply more amps then you need. If you had an adapter that supplied less that you needed, it would still be fine, but then you might have trouble running the Zaurus with a power hungry CF card, the backlight at full, and still recharge the battery.