Nothing free AFAIK. IBM InkManager is the closest thing, but you arguably need a CrossPad to justify a license.
Your best bets would be either Phatware's PenOffice or the (Meander?) Word annotation program. Not quite ink, but close. PenOffice has a 30-day demo last I checked, and is well worth the price to my mind.
If you get PenOffice you could also get PhatPad (if your system is fast enough) which will get you ink capabilities in that app.