A solution has been around for some time, but a client reminded me about it today so I'm sharing it with you. ritePen from EverNote is an alternative to the Microsoft tablet input panel. In addition, ritePen gives you the ability to "write anywhere", a feature found in the first version of the MS TIP but subsequently removed. Using the Write Anywhere feature, you can ink directly into a document and have it converted to text without first entering it into a special area like the tablet input panel.
ritePen costs only $29.95 and more information is available at their website.