If you're using this new tv for gaming, movies and pc usage, i wouldn't recommend getting a plasma:
-burn in can still be an issue, and while panasonics do a good job using pixel shifting technology, its not worth spending all this money and having a burned in image if you leave something up for a more than like a half hour or hour or so
-also if your room is really bright, plasmas have glass/plastic screens which reflect a good amount, whereas lcds do not
Also I would put LCDs over DLP televisions because of the clarity, while you can go much larger for the price with DLPs, the good clarity on a quality LCD still outshines a decent picture with a larger size.
About the newer LCD's 120hz refresh rate:
-hardly noticeble if you're just an average viewer of tv, it's extremely hard to tell the difference
-if you're an avid sports watcher this might be important to you, but you really won't be missing much if you skip out on the 120hz and save the money
Sony and samsung are definitly the two best LCD pictures out there, either of them you can't go wrong with