Plasma would give you the equivalent of 120Hz processing, so your motion for both games and TV will be designed for the reactionary picture of a video game system. The LNxxA550 units are 60hz.

Then there's the image retention or burn-in issue. If you handle your panel with care for the first 200 hours and monitor the panel using the "All white" setting (to see if you can see images in the panel), then you should be okay. But extended gaming and "RPM" indicators in driving games, say, might prove to be an issue if viewed more than 10-20% of the viewing time.

The more particular and careful you are with a plasma, the better you'll be. The fact that you took the time to ask the question indicates that you'll probably take the time and provide the minimum care and attention to keep the panel looking good.

Either way is a winner. If you're a huge gamer, and I mean 40-50% of your time will be games, then I'd recommend the A550 LCD, and maybe the A650 LCD for the 120Hz capabilities.

If you have further questions, let me know. We're here to help.