I don't think you will be dissapointed in either. Plasma has the advantage in terms of very fast moving images - but you can't really notice too much on either, unless it is a very large TV and you are sitting close to it. Plasma is known for having a truer picture (but the only noticeable difference will be in the darkness and in true blacks - the hardest thing for a tv to replicate - and in high end models there will be little to no difference).

Plasmas don't really have the image burn issue. Actually any television that is left on the same image for a couple days will burn just the same. In the past when plasmas ran hotter they were having that problem with games that had a display that remained stationary (like a racing game with a speedo that was fixed in the corner). But those issues have been resolved.

But in short, both will be fine, and you will love thet PS3. I'm still and xbox 360 guy, but have played a bunch on a ps3.