Hi everyone! Just passing by to report on The Longest Journey. (edit: I am using the GOG version, build 161)
The problem with the mouse trail can be solved by disabling hardware acceleration for the game. To do that one must edit the file "preferences.ini", but NOT the one on the game's main folder; there's another one on AppData folder (something like C:\Documents and Settings\User\Application Data\The Longest Journey). The following line must be on the file under [DirectX] (if it's there but different change it, or else add it):
bool_UseHardware=0
This will solve the mouse trail problem (at least it did for me).
There's also a bit of sound stuttering when using the default audio device. I solved it with the following line under [Preferences] (you can also change it with the game's config application, found on the game's main folder):
AudioDevice=winmm
The audio gets a bit of a delay (less than one second) but, to me, it sounds better than before.
Also, as with many other games, getting it to run properly on fullscreen may be a problem. Instead of stretching the image to the size of the monitor, the game will run in a small rectangle in the middle of the screen, with the size of 640x480. What I do is, I use VB's Scale Mode and resize the window to a perfect 4:3 resolution like 1024x768 (on Debian Linux I use the command "wmctrl").
Hope it helps!