2003 is ink enabled.
If your table is running tablet edition and has the active digitizer then
the from will open in ink mode automatically.
there should be a button in the toolbar to turn this off.
You can also use the ink control in your forms.
This functionality is all based on the OS and tablet and cannot be used on
other computers / OS. Although Vista includes inking too.

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Clay Fox / Microsoft InfoPath MVP
www.InfoPathDev.com / The InfoPath Authority / Downloads, Samples, How-To,
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> Is InfoPath 2003 designed for Tablet PC?
>
> I was testing a xsn file on a tablet pc with window XP professional. It
> switched into an ink drawing mode sometimes when I tried to enter a field by
> using the on-screen keyboard and the calender is not functioning at all. This
> file is running fine on a regular pc with the same OS. Please help.