<Updated>See here for information on Vista support for the Toshiba M7/R25 Tablets</Updated>
This is from my stack:
Vista beta drivers and utilities for selected Toshiba machines (especially newer Tablet PC’s like the M400/M4 and the R25 (use the M400 drivers)) have been made available here.
They aren’t too stable, but they are better than nothing.
(BTW: Use the XP Screen Rotation Utility since one isn’t included in the updated list)