MH, I've recently got a similar system going very well and am "current" on this topic, but you don't give much background info so I have to make some assumptions.
You're on 98 with a software player and the movies play well on the notebook screen.
You can't see the Notebook's "desktop" properly on the TV either. If you can, the problem is with the player you're using.
You're using the correct lead.
So, assuming that the problem is with the Notebook graphics setup;
Step One: start in the BIOS during boot up and check that the TV output is set to PAL not NTSC.
Step Two: go to your display set up dialogue boxes in the contol panel; also available by right clicking an open area of the screen and choosing "settings". Then go Settings/Advanced/Displays and look around for something out of place (I'm basing this on my ATI Rage LT PRO AGP setup so can't be more specific).
Still no luck? Then right click "My Computer" and select properties. Then select the "Device Manager" tab and look at the the Display adapter(s) to see if an error is reported. You may be invited to re-install your drivers.
While you're there, check your "Other Devices" and see if any devices (eg PCI Multimedia Video) are having problems.
That's enough for now; I'll need more info to go any further. Good Luck.