I'm not an expert on the Panasonic series 5 plasmas, as I don't own one (yet), but I would definately make use of the 3:2 pulldown circuit.
As I understand it, on the series 5 displays, the 3:2 detection only works on NTSC (region 1) dvds, so not all sources will benefit.
3:2 pulldown is designed to reduce jagged lines which are visible when movement occurs in a film.
If you have any region 1 dvds, play a scene from one that involves a slow, horizontal pan, such as the scene in chapter 26 of Gladiator, when the camera moves slowly across the arena just before Commodus and Maximus emerge.
With 3:2 pulldown activated, such scenes should look smoother. However, there is a lot of variation in the performance of motion detection chips which are built into displays. Some can look very good, rivaling the performance of a progressive scan dvd player, while others can be quite crude. Hopefully, the 3:2 pulldown on the Panasonic will be good.
Regards,
Bob.