also, instead of using tightvnc...
use krfb
or even better, x11vnc.
The difference between the two is, really.. krfb is a graphical client that you can access from the K menu, but it requires manual invitation and acceptance to use the screen each time.... while x11vnc you start from the command line, but it will allow access without invitation...
weigh the difference, and apt-get install the appropriate one.
either way, the tightvnc client for windows has no problem communicating with either.
-Thom