I recently installed Houdini apprentice, however when I try to run Houdini the splash image comes up and then disappears and the program does not start.

Edit: When houdini starts it leaves an hkey process running but nothing happens, also when I try to run the licensing program alone the process is in the task manager but nothing happens as well.

I am running it on vista x64 home premium
geforce 8400 with the latest drivers
3gb ram
intel core2duo t8100

Try re-installing, and choose license server as an option.
Also make sure your firewall is not blocking the license server from downloading the Apprentice license.

I would try to disable my firewall just for like 5 minutes, to see if that is the problem.